Over heating engine - Head Gasket?

Managed to source an engineer who knows the V8 engines well and is willing to work on my engine. Attempted to drive to his workshop (20 mins from home) but after 5 mins engine overheated again - limped back home after waiting a while for it to cool down. Call me a pesimist but my worry is if the head does come off and the engineer finds additional damage apart from a blown HG, - do I keep throwing money at the engine? I know P38 enthusiasts will say yes but (with limited funds) should I get myself a decent run around (~£2000) instead and see what I can get for a non - runner (but in good nick) P38. Decisions decisions!!!:confused2:.

when the heads are removed you can test the block,
block of 2 water channels at rear of block,
2 small hole water channels at front of block,block 1 of and use a tyre valve in the other 1, make sure there is water in the block and using the tyre valve you can now apply a small amount of air pressure into the block if you have a problem you will see water bubbling up the side of 1 or more liners.