engine rebuild cost WAG!
The rebuild cost -- parts, machine shop work, tech labor is a real big guess because 'it depends'.
The valve guides and valves may need replacing, valve seats refaced.the camshaft, rockers, shims, cam tower bearings, timing chain and guides, oil pump, pistons, rings, boring the cylinders, decking and line boring the block, boiling out the block, replacing distributor drive shaft bushings, rebuilding distributor, rebuilding alternator, starter, fuel system, reconditioning both ends of the rods, crank polishing, balancing and cleaning,cleaning and careful reassembly. Could be lots of work
A first class job (not full race blueprint) could easily cost $8K
Usually far better to buy a good remanufactured engine assembly ready to bolt in.