Hello and welcome to Just Answer!
I am not sure what you mean when you said "forward solenoid pressure". There is no such thing on a 46re transmission.
The 1st, 2nd and 3rd gears are hydraulically controlled and the upshifts are controlled by the electronic governor solenoid.
If you can't get it to engage into drive, you either have a valve body issue or a leak in the forward clutch circuit. A leak in the circuit will usually show up more when the transmission is warm instead of cold.
The governor pressure is fluctuating way to much and the most common cause is the solenoid. I have had new faulty solenoids before and I started using Borg Warner solenoids now because I have seen to much trouble with the Dodge ones. The Borg Warner doesn't have a permanent magnet in them, so they won't attract metal filings like the oem one.
Did you completely disassemble the valve body when you overhauled it?
What was it doing before you rebuilt the transmission? Are any of the problems that were there before still there?
The third test in the service manual will test both front and rear(forward) clutch circuits.
Do you still have the service manual?
Yes, you should have low pressure at the accumulator port if the forward clutch was leaking. You shouldn't need to check the front servo to test for leakage in the forward clutch. If you went through the first three tests and your forward clutch was leaking, you should have been able to tell by the pressure reading.
I do think you have a valve body issue and will need to pull it out and go through it again, or have it tested. There are some transmission shops that have a valve body tester and they can test valve bodies before installing them.
I have overhauled a ton of these valve bodies and even I sometimes can overlook or miss something during the overhaul.