The pre 69 blocks were the strongest due to the highest nickel content and thicker main webbings. 70-74 were strong too but not as strong as the pre 69. all these were non-roller which means you can use a hydralic roller cam. in 86 the came out with the roller blocks i think. You can roller blocks in grand marquies, crown vics, explorers, alot of things at the junk yard... so that might be the cheapest route. So far into my swap I spent, 100 on motor mounts, and the price of my motor but you werent including that, fuel cell which was 150, headers which were 150, I traded a shot 351c for my tranny, got my truck for 200 bucks, spent 200 on my shifter, spent 440 on my stall converter, spent 125 for the rebuild/shift kit for my tranny, and got my oil relocator for free, and my radiator for free. so about $1400 all together and i still need tires and a rear which im going to the junk yard tomorrow to fetch. The junkyard near me charges $35 bucks a rear