A 30 over 318 with a 4"stroke is 390.6 cid. There is no 360 with equal heads, cam, and compression, ever going to out work it (it's 30 cubic inches smaller). As stated any magnum engine will need heads, and any LA 360 is going to require the same investment as your 318 with the stroke crank. If you build this to the 400 horse 318 specs with the stroke crank you will easily meet your goals and then some. Check summit for the cost of a 318/340 cast 4" stroke crank. Then check with your machine shop on the cost of a crankgrind, add that to purchase price of the 360,and compare your options

Randy