360 compression ratio, Am I wasting my time?

Well the major concern with going with the magnum heads is I can't use the Ld 340 intake that I want to use and the stock 340 valve covers. This was a factory 273 Auto, P/S,A/C car. Witch I'm in the process of putting the A/C and P/S back on. Not looking to make a race car just a nice street car with 68-70 340 type performance. The car has a 727 with the 10 3/4 factory high stall convertor and a 8 1/4 3.21 SG. I will ID the cam when I take it apart and I'll post my findings along with the calculated Comp. ratio. Thanks for everyones feed back. What about using the 273 #920 Head?