There is enough meat to do a 8.ish to 1 compression ratio, you can get forged pistons for the engine, which works out at £800 ish, but you will still have to machine them.

The con rods are strong enough for 600bhp and I think the crank is fine for that bhp.

The timing chain is not difficult you can do with engine in place.

what fueling are you using eg mangment and injectors?