i dont know so much on if there is availability on new repro blocks for flatheads, but to put it simple... to build one that will keep up with a modern SBC you're looking at well over $10k to build you motor.... to do a simple rebuild and get about 90-120HP depending on which motor you're doing... you're looking at spending at least $4k.... now if that hasn't run you off.... i'll let ya know you're going to need torque wrench, a machine shop to bore your block, a piston ring installer, a piston ring compressor, a valve spring compressor, a cam bearing installer... i'm sure theres more i'm forgetting(when you have everything you need you forget what you wouldn't have with a basic toolkit) rebuilding a flathead is yes simple... but these days its very pricey.... if the only reason you want to do a flat head is for simplicity to build... i'd reccomend just sticking with an overhead valve engine, you'll save a ton of money and get a lot of performance.... if you've got the funds and you want a flathead for keeping your car semi original then go for it

BTW you wont need a torch on a basic rebuild.... except for maybe heating up wrist pins but you can have a machinst attach pistons to rods when you get everything balanced