These systems come in 3 basic configurations...the systems you buy must suit the duct lay out you have and the location of the indoor unit... the 3 types are:
1. Upflow, sitting vertically in a closet and discharging air upward
2. Downflow, sitting vertically in a closet and discharging air downward.
3 Horizontal, sitting in an attic space or crawl space mounted horizonatally and
discharging air in one end and blowing it out the other.
Without that data I cannot tell you if the 16 seer Nordyne unit will work or not.
I am in San Francisco, California.. I have done projects in 20 or 30 states. I use the ASHRAE guide (the industry standard) to estimate heat loads according to the climate zone a home is located in.
In other words you need a very different system for San Diego California near the coast, warm, dry, low humidity...than you need in Florida on the coast, hot, 98% and 98% humidity.... etc.
Northern climates present yet another set of issues. You need a high seer rating in extreme climates, and not so much in milder climates.
The EST time zone you mention spans the hot and exceptionally humid state of Florida, and the much cooler and much less humid state of Maine...and a bunch of other regions in between....
.....and within those regions are homes directly near the ocean, and homes several hundred miles inland... all of those with radically differing heat and cooling load issues.
That is why I ask you which direction you are in from the center of the nearest city... it is a primary factor in estimating air conditioner sizing.... a vital factor actually. So if you can let me know about that, I will appreciate it.
Another factor regarding equipment selection...if you do this job by taking out a building permit as the law requires is a 'Title 24 Load calculation', that is done by protocols defined in the states 'Manual J'
Beyond that, the length of the and size of each air duct is a vital issue in how large a heat pump that can be installed and function correctly. Any mistakes in these areas results in a less than optimal or outright poorly functioning system.
Standard practice is to have a state licensed HVAC contractor arrive, do a manual J heat load and duct sizing calculation and then select the equipment accordingly... quality of the contractors of course varies... on average about 30% of projects end up with design issues to one degree or the other... and that is after 4 or 5 hours of load calculations, duct sizing and filling out state required paper work.
Thats an over view. I can help you however get into the ball park...I can ask you questions and explain in extensive detail why I need the answers... so that I can help you buy a system that will most likely be optimal for your application and budget, and hopefully can be adjusted and modified by your friend to achieve a workable system...
Its not done casually however... it is extensively time consuming, If I help you find the equipment and do the necessary searches it will take me between 10 and 20 hours.
That of course does not fit this venue.
What will work as I mentioned earlier is if you can tell me the nearest city etc..and then do the searching for equipment yourself according to my sizing estimates... then let me know what you have found by providing a link.... and then I can look at it and advise.. that will only take me a few hours..and fits our venue here.
If you really mean what you say and want the lowest price, then you and I can spend the extensive amount of time it will take to find a refrigerant 22 system... if you are not that serious about price, it will be a lot easier to locate a refrigerant 410a system....
That aspect is up to you of course, and I have given you links to ebay so you can do that search... let me know if you need coaching beyond what I have given about the use of the relevant key words in doing the ebay search.
From the data given so far the air ducts are most likely sized to accommodate 2 tons upstairs and 2 or 3 tons down stairs...needed heavy back up electrical resistance heat if you are on the north east and little or none if you are in the south east. I stell need the configuration as mentioned at the top of the post..
If you are willing to pay usual prices, about 20% over wholesale you can get by with a lot less searching.
If you can give me the brand and model number and btu rating of the equipment you removed, and tell me how it worked, then from that I can assess almost exactly what will work.
Let me know if all that makes any sense on your end or not...and answer what you can, we can go from there.