I say that jokingly of course. It may be my age or just getting to use to driving more modern vehicles but being able to cruis down the road hiway at 2200 RPM is a joy to me. Both in terms of engine noise and MPG. In our old cars trying to have a decent option for a transmision with 4 or more gears is a expnsive endeavor. There are of course varying opinions on gear compromise. I loved my 77 GP when it had 3:23 gears. I didn't care for the 3:42 I put in years later or the 3:73 gears my brother put in his TA that also had 3:23 previously. I have a 455 in my FB as I mentioned with the 3:36 gear and trying to hold it at 55-60mph is no different then putting it Neutral and and trying to hold the RPM at 2500 and the 2.5 droning exhaust is just annoying.

My Tempest I bought two years ago with the 2:56 with the 326 and 2 speed has been something different for me to experience and I just love it. It can hardly get out of its own way but that is another story. Its still the one I can just jump in anytime and drive.

The car weight, motor size, cam and converter all play a part in whether it all works well. But since the OP already has the 3:55 gears it sounds like he knows what he wants. I would say to the OP go with the th350. It should slid right in without any changes to the cooling lines, converter, cross member or driveshaft. You will need to a linkage connection for the kick down but that should be it.

Since you say you already have the 3:55 did you buy a new center section? in mind has he bought a new center section?

There were 3 different ratio 8.2 Pontiac 10bolt carriers for both single track & Safe-T-Track usage
High ratio = 2.56-2.78
Mid ratio = 2.93-3.08-3.23
Low ratio = 3.36-3.55-3.90-4.11-4.33-4.56-4.88 Eaton posi for the 8.2 only in Low Ratio