i have an old 62 T-bird and I was thinking about putting a newer engine in it. I was looking for any advice for the most appropriate engine or any advice on the subject. A 390 6.4L is the engine that is supposed to be in it.

 

If the car is in good shape as a collector, I would not make a swap like that unless you really want to do it.
Most I would do is consider a 427/428 or 460 big block carburetor motor that should about bolt in.
Otherwise your in for reharrness/rewire a complete computer control.
The trans would have to be changed along with the motor to an electric type.
These kinds of changes get really involved with a lot of custom parts and mods from mounts to exhaust to cooling to instrumentation.
The bottom line is you have to be the resident expert on the project when it's all done because no one else knows about it if you have issues.
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I did a 73 Mercury Comet GT with retrofitting the old 302 to fuel injection.
For example, fuel injection uses 2 OX sensor. The issue is the old motor has a different fire order that messes with the feedback signal timing of the OX sensors.
The trans kick-down is all oppisite for control arm movement when using throttle body actuation by cable to a c4 auto trans. The AOD control cable was reused. your car likely has a C6 the big brother to the C4.
The exhaust had to be all custom.
Fuel tank has to be fitted for fuel injection with a two pipe high pressure pump and pickup area so the pump does not run out of fuel on acceleration etc.
Unless your up to the project go with a more boltin motor and watch the hood clearance for a problem.
I once had an 76 F250HD with the 390 and 4 barrel. What a powerhouse that truck was. Find one of those engines and rebuild it and you should be happy with the power as just a drop in.
Anything can be done if time and expense is no problem.
Good luck.