Hi, glad to be of help. Align the TDC mark with both valves closed on #1 cyl. There is only 1 TDC on compression stroke but the TDC mark will also come up on exhaust stroke so to be sure you have #1 TDC, both intake & exhaust valves on #1 must be closed. The distributor may not always line up to your oil pump drive to drop in all the way but as long as you have it lined up to #1, you can tap the engine slightly till it drops in then recheck it. Let me know if you need more help.
You could also use a long screwdriver to line up the oil pump drive but it's easier if you just drop distributor in lined up to number one on the cap hold slight downward pressure on distributor and tap engine till it drops all the way. The distributor gear will be lined up with the cam gear when you first drop it in and turning engine will line it up to oil pump drive. Once it's in all the way bring it back to #1 TDC with both valves closed on #1 and make sure rotor is pointing to number 1 on the cap. Once everything is in, Disconnect the brown wire w/ black stripe on the pass side firewall under the plastic cover. Hook up your timing light, start engine and adjust to 0* by turning your dist. Shut off motor, reconnect brown wire, start engine and watch the computer adjust the timing. That should do it.