what size cam???

Make sure you're honest with yourself about what you expect from this engine, and how you'll be driving it 90% of the time. As BJR mentioned, don't overcam it if you're driving it around town or on the highway 90% of the time and only go to the strip once or twice a year, because you'll end up with a high RPM screamer but a dog off the line. Match your cam to your heads and especially to your rear gears. If you have the cash, put a set of pistons in there to get your compression up to a true 9:1 plus range, match your valve springs to your cam, which shouldn't need dual springs, and save yourself the money for the extra head work. Depending on the year of that 360, you should have a decent set of heads on it, so just get a good 3 angle valve job done along with the normal head rebuild work, use a steel shim head gasket, and go have some fun. I run an old DC 484 Purple Shaft cam, 915 heads with a 3 angle valve job, steel shim head gaskets, windage tray, LD340 manifold, 625 Carter carb, duals through the original 273 manifolds, and 3:23 gears in my 66 and it will tear the doors off most of the Stangs and Maros around. Plan your engine build with a combination of parts that complement each other and you won't be disappointed. Remember, bigger isn't always better. :) Good luck.