Flatheads
The first this to say is a well built flatty has a sound all of it's own, and when done right they look better than the wife's diamond rings, and cost more also !!!
I started with a good block from my 49 no cracks, I just got lucky! it did have a few rust spots from water sitting in the cylinders, sent it to a good friend and old time machine guy that did flatty's back in the 60's, bored it to 125 to clean up all the spots, worked the entire block. line bore, hardended seats, cam bearings ect. I purchased a good 4" merc crank, 10-10 cleaned it right up, new pistons, balanced everything, shot peened, relived the top of the block around the valves, he polished out and worked the intake and exhaust ports, all new valves, springs, guides, locks, lifters ect. new oil pump, water pumps, gaskets and seals ect. I sent my stock cam up to wash. state. and had it reground, I opted out of the alum heads, and found a good set of merc. heads, I may still go alum. used intake manifold and old carbs, all the parts to set up 3 carbs, all rebuild parts, new shafts, power valve for 1 and plugs for the others, new shafts and plates, primary and secondary, I can put it all to geather so no cash out of my pocket there, after it's all said and done I hope for 175 to 185 hp. so I get an extra 75 to 85hp over stock, and it only cost me about $4000.00
Now if you want to get over the 200 hp range you need to put a blower on top of it, it will only pull in so much air on its own, and to make power you need more air, so add another $4000.00 and you can get over the 200 mark, now put a t5 set up behind it with a 4:11 rear end $1500.00 and you will have a traffic light screamer and interstate cruiser that will take out most of the kids on the road today, and some old muscle cars, they will scratch there heads wondering how you beat them.
I do love flatheads.