Has a 305TPI/Auto. Would like to go 350TPI next go-around. Please explain to a GM illiterate (me) what I need to be looking for.....
What year(s) 350 block
What heads
Can I re-use my existing TPI
plus any other helpful info.

This car will be a driver, and not see any track time or severe beatings. Thanks!

its been dont many times over. a quick search will yield all the info you want(and some you didnt know you needed).

80vettevert, welcome aboard thirdgen.org.

The quickest, easiest, and cheapest route to 350 would be to get an '87-'95 light truck engine. Your TPI and everything needed will transfer from the 305 to the 350. It'll work fine without any changes to the TPI.

A couple notes of caution: It won't be a barn-burner; and I've seen a few of those engines have rod bearing failure.

And, make sure before you buy it that it's a 350 and not a 305.

Yes you will need to change things like injectors 305 has 19# and 350 has 22# a retune also on te ecu and or a 86-88 trans am it was only a few I think 2 350 (L98) camaro in 87. Don't use truck cam. What's your HP goal better what do u want to run in a 1/4 mile I run a 13.6 with a 305 I beat plenty of cars with twice as much hp I beat LS1 fbody too I will be swaping my motor too to a 383. But if u want a mean 305 cam full exhaust tune new injectors and a procharger get a 9bolt rear end 3.27 u will run in the 12s.
But few things if u want a 350 with little more kick than a stock 305 new base and runners stock tb port what every heads if they are stock would do vortech heads mild cam headers shorties and a taller rear gear no need for a 3.73 if u running a 700r4 please don't swap the 700 for a 350 or a 400 **** even a powr glid if u swap trans put a newer one in 480le t56 that stuff. I have some 22# injector for sale. Oh a good shift kit will make u fell faster than u going lol it do help a lil. I hope any of this help

Given this:
All of this:
...is pretty much moot.

Nothing needs to be changed for a DD.