The block and heads are pretty much the same for 360/390 engines. Both have a 4.05 bore. Really the only way to tell is to drop the pan and look at the rods and crank. The 360 has the shorter 3.50 stroke and the longer rods. Get the casting number off the crank and one of the rods if you can see it. Post the numbers here and then we can tell what you have. The 360 crank will have a 2T or 2TA casting number and should be on the 7th counerweight. G.