small block cylinder heads NO magnums

Got a question for you engine guys. I got my 273 apart. It's in good shape. Bore is +.030.
Some were in its life, someone installed a set of open chamber 318 heads(low compression)  and hydraulic cam& lifters:) .
Since I've got open chamber heads. I would like some more compression. I could get these heads milled (a bunch)/ or install a set of 85-89 318 fastburn 302 heads closed chamber (higher compression). I can get a set of 302 heads for $100. if I pull them.
Either heads (my open chambers or the 302s) should have some valve work.
My question is...would you mill the open chamber heads & get the valves done ? or
Buy the 302 heads $100. then get the valve done ?
NO 360 heads/ no magnum heads/ no putting in bigger valves. Just a possible head swap and valve job .

Figure out everything you will need in both cases.
If you mill the old heads, you also have to mill the intake face so things line up. You usually end up with stuff that is tough to align and keep sealed.
I'd also strongly consider exhaust seats for them. I'd expect at least 6-700 in machine shop costs.

If you use the magnums, you have to get pushrods at least. You may need lifters (pushrod oiling). Look into rocker arms too, and valve covers. I think the early covers bolt onto late, but the later seal better. I do know that they ran mag heads without roller lifters for a couple years (87-89?).
Solid cam or hyd in the 273? IIRC, you said hyd. Check to see if the pushrods are already figured out and stocked or if you have to measure it out and get them custom made. Also make sure the valves don't overhang the small bore before getting too deep.