The 350 heads were for a 4" bore so the valves will be shrouded, in this case smaller chamber heads would be better.
You probably need what they call "double hump" heads. They seem to be the stock heads with the largest valves and they were for the 283/327 motors.
The 602 casting heads found on 305 engines have smaller combustion chambers than the factory Power packs and larger 184 intake valves and are unleaded compatable. The 283 can handle the larger 194 intake 350 heads there will not be any (shrouding) the 202 intake valves are bit bit much for a 283. Its the large open chamber that will lower the compression ratio. Now if you add a supercharger?
For a 283, DO NOT use heads meant for a 350, or even the 327 Camel Hump/Double Hump heads (unless you have some serious domes on the 283 pistons). The smallest chambers the Double Humps had, were the 461X castings with 62 CC's; the rest had 64 CC's. 350 heads could have as large as 76 CC chambers! They all have way more chamber volume than 283 heads, Power Pack or otherwise. However, there are some 70 CC chamber truck heads with the Power Pack markings; stay away from those as well. If you want a "newer" head, then go with the casting number 601 heads with 53 CC chambers. If you find 601 HO heads, then you'll get the 1.84 intakes, otherwise, they will have 1.72 intakes. Both are fine for a street 283, and have hardened exhaust seats. Anything with 64 CC chambers or bigger, you are losing CR. With these small CID, small bore, short stroke engines (265/283) it's hard to build any kind of CR. Look at the size of the domes on the 302 Z-28 engines with the same 3" stroke of the 265/283. The 265 heads came in right around 56 CC's, the 283's around 60 CC's. This is one case where smaller is better! I am Butch/56sedandelivery.
What about it? The 307 had flat top Pistons, steel shim gaskets, 76 cc combustion chambers and that equals very low compression. Purposefully built that way by Chevy engineering to reduce NOx emissions by not allowing the NOx to form.
Something else to consider, if you run late heads on an early engine; you might as well just use a 350; because it won't look any different. Just saying.
Lots of times someone wants to use what they have. say you got a 283 or 307 and all it needs is a set of rings and bearings. and they don't want to spend mega dollars updating a set of original heads. They can find small chamber 305 heads and simply clean them up lap the valves and have a streetable engine that will run very well on pump gas at very reasonable cost. And it will not guzzle gas like a 350 does. Back in the day we used double hump 194 intake heads on 283,s very successfully. Usually bored .060 nd a steel shim head gasket. sometimes the heads would be milled and the intake milled to fit. But we had really good gas available at the pump. My 1957 chevy dump truck has a 307 that got new rings and rod bearings and new timing chain. and a set of thick gaskets & 305 heads. I didn't do anything to the heads but spray them with oven cleaner and wash it off with a garden hose. Then I wire brushed the carbon from the chambers with a drill. That engine pulls better and uses less fuel than the original 261 six it did have.
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