If I remember right if it's a 74 360 4bbl then it's basically a 360 2bbl, with a 340 cam and a 4bbl intake and carb. Meaning it has about ~8.8 to 1 compression. If the pistons have a dish in them then 360 2bbl if they have 4 valve notch then it's like a 73 340 about 9.0 to 1