Does the rest of the engine need a rebuild ?, the stem seals are very easy to do on this without even removing the head.
If it needs a rebuild, then I'd say defo under £500 for complete new parts/machining.
The pinto cams usually have plenty enough lobe on them that they can be reprofiled, I've used reprofiled cams including on pintos for around 25 years, without any problem.
The advantage to a reprofiled is it is already work hardened metal, and cost, around £50.
The pinto responds exceptionally well to head porting, you might as well also go +90 thou V6(colonge) pistons when it's bored(assuming it's needed) and get near 2.1 litre, run 1 thou extra bore clearance make sit much freer revving, lighten the flywheel, the flywheel is a massively overlooked area that's effectively free power with zero drawback for most.
Depends on how fast can you afford/want to go ?
tabetha