Yes the springs will work on any LA, shaft mounted rocker small block mopar head.
the cheapest way is as suggested above. If the 360 heads are in good condition, and dont need a valve job, have them milled to bring the Comp ratio up and have the intake sides of the heads milled so you dont have intake fitment issues. Should not be more than 200-300 $.
To decide how much to mill, you need to know your piston deck height - the height of the piston(s) at maximum upward travel relative to the deck of the block. CCing the heads would be nice, but I would assume them to be around 72-73 cc's, (anyone - please correct me if you think I am wrong). You then need to calculate the compression ratio based on the measurements and some geometric calculations (cyl volume), dont forget to add in the cc's of the head gasket, for felpros they are around 8-9 cc's. There is a standard amount to mill from the intake side depending on the amount taken from the block surface.
Your compression ratio is then: (the volume of the cylinder at BDC + the volume of the piston deck height at TDC + the volume of the gasket + the vol of the head) divided by (the cyl head vol + gasket vol +the deck height volume). Change the cc's on the head to get where you need to go.
Depending on how much is milled you may need to space the rocker shafts to make up for the difference being taken from the head to block surface, there are spacers sold that accomplish this cheaply.
Somebody needs to chime in about the relationship of milled amounts to cc's and the intake correction figures. I dont have this at my finger tips.
What would help you is to buy a good small block mopar hop up book. Larry Shepard wrote a very good book on the topic for your purposes, called how to rod small block mopar engines.
Hopefully this helps.
