im planning on taking out my old block which is a 305 and putting a new one, just putting back on my intake and oil pan and bolting everything back on to the front. but was wondering while im changing it should i put a 350 in it? im getting the new block from oreilys which there blocks are done by a brand called powertorque(would like to know opinions on these, if anyone has used them before) but my real question is, if i wanted to take out the 305 and put a 350 block in it. what else would i need to do. ive heard the intake will bolt back to it.but what new stuff will i need to get?

Nothing , the blocks are identical
Depending on the year of the new engine you may need a new oil pan and flexplate

Intake bolts to the heads , not the block
Depending on the year of the replacement engine ( you don't state what year you have , fill in your profile )
the heads may have a different angle on the 4 center bolts holding the intake on ( easy fix )
Also the holes at the front where the accessories bolt on vary across the years so you need to check the holes on the new heads match the ones on your 305.

its an 86,

The new engine or the old engine? There are two engines involved and to know whether things will bolt on you/we need to know the years of both.

Also if you go with a 350 you will need to change the injectors to 22lbs and get a chip for a 350. Since youhave an 86, a chip for an 87 and 88 350 camaro or firebird will work. 86-89 has the same computer but the 89 has VATS in it and you dont need that.

If you go to a 350 PLEASE DO NOT put the 305 heads on there! Worst idea ive ever heard people make! They are not good heads! Hence the fact why you need to know what your intake centerbolts look like to know what heads to use for your intake to bolt back on!

the old engine is a 305. and the new one is the mentioned above made by powertorque its an engine company through oreilys. i was also wondering if anyone had heard of them or used them

The 416 and 081 heads are far superior to the vast majority of 70s 350 heads, and if youre dealing with a crappy 70s farm truck 350 with low compression, you could do a WHOLE lot worse than either of those 305 heads. They're actually very good. The only reason theyre not on more 350s is because the compression ratio with flat tops is so high and the valves are smaller than mids 80s+ 350 heads.