Stock 304 blocks require small relief around the valves to get the 360 head to fit.
360 heads will flow a bit better, but you have a distinct possibility of the valves hitting the block. The .030 overbore should negate that,
however,
given the tight clearances between the block and the valves, I think what marginal flow you get with the bigger heads will be negated.

 

I assume the short block is a 360. Yes, the heads will bolt on. Did they cut them for studs or are you going to use the bridges. If you don't know post a couple pics of them.
I'd have to look at years but there is a switch in there for 7/16 and 1/2 head bolts. I think it was right around that year. I'm sure someone will chime in.

 

Yes I have a 360 short block. The 401 heads that I see listed for sale are late 1971 heads. They are pivot style rockers not bridged. According to AMC chart all the dog legged exhaust port type heads 360/401 use 1/2 head bolts. Just like to confirm.

 

Looks like they changed in 70 so I'd think you're good. I know 72 was 1/2 because I have a set.

 

The AMC forum can also advise, and they will probably have a ton of input, from more folks that swap parts around like you are wanting clarification on. Yes we have a few here, but if needed.....another resource to look at.

The AMC Forum

Discussion forum for American Motors cars and products, restoration details and more.

theamcforum.com

 

If I remember correctly, all 401s had dog-leg exhaust ports, so they should use 1/2" head bolts. They went from single to bridge rocker design in '74..

So, the 401 heads should work fine on your 360 block.

Good luck

 

Thank you all for your guidance. I received pictures from seller and some of the intake valves look pitted and some of the exhaust valves look like they've been replaced. Hasn't been really tested for cracks either. Thinking I might steer clear of these particular heads and continue to search.