360 build ????s

$250 is a hard deal to pass up!
But, before you put money into that 360, have a look at how far down in the hole those pistons are,and check also to see if the piston tops have valve reliefs in them, or if they are plain flat-tops.Bring a piston to the top, exactly to the top,and measure with a precision measuring tool.With this figure and the head CCs, we can determine fairly closely your Scr. From that it becomes possible to juggle Dcrs and ICAs, to arrive at a cam choice that works for your available gas, and that meets your performance goals. With out the Scr, I, at least am blind, fumbling in the dark,just plain guessing.
For the 360; you will need to know if any balancing was done. If nothing else try to get the oem harmonic balancer. If no good answer come as to balancing,be prepared to have it done.
You will need; oilpump,pickup,A-body oilpan,Performance timing chain set,one engine bracket(drivers side I think),a 360 gasket set, and the cam kit.
You will be able to reuse the 273 arms(if in good shape), the timing cover, the cam T-plate,and everything else from the decks up.
We wont know about the pushrods until after mock-up.
This assumes the short block is otherwise complete including all new bearings and rings, etc.

Just in case you're not familiar;Scr is static compression ratio, Dcr is Dyamic compression ratio, and ICA is intake closing angle.
The measurement from the top of the piston to the deck surface is called Deck Height, and is measured in thousands of an inch(like feeler gauges) and the tool that does the measuring is a Vernier Caliper, or a Dial Caliper.