adhoc1979 wrote: Questions. Best next step? Replacement engine or strip down in an attempt to repair. Whats the likely hood of shearing more bolts? (apart from very likely)
So back to the OPs questions, the risk of shearing more studs on strip down is rather academic now, as the case will almost certainly need splitting to remove and replace the corroded studs. Once in there that far, it's pretty pointless to rebuild without checking/replacing all the worn parts. So, in other words, the moment a stud breaks you're most probably looking at a full rebuild.
Cost wise, it can be over £2k in new parts alone before counting the labour to build and test it. Eg an early DG I built had pretty much new everything except case and crank, inc AMC heads, NOS genuine VW camshaft, NOS conrods, new pistons and barrels, SpeedShop stainless exhaust and refurbished carb. Came out at a touch over £4k (exchange, pre-run and tested, fitted, 2yr warranty).
Whilst that is the top end, others may prefer a more minimum-cost approach. This is also doable, with some re-used parts in good condition (mainly heads, cam, pistons and barrels) but it is certainly not a fully reconditioned engine, and would not carry our full 2 year warranty, but 6 or 12 months dependant on spec. (Yes I could put together an engine from my parts bin, paint it and call it a recon, but I won't. All engines are built to order and come with SD card full of pics of your build so you can see everything that's inside.)
Your other option, as mentioned, is to find a used engine. Nothing wrong with that, and obviously a good running but well-used one is a lot better than a bad rebuild!
As an aside, an earlier post stated I don't offer a warranty, but was rather ambiguous in its wording. It actually referred to me fitting used engines, AAZs etc. I cannot offer any warranty on unknown used engines, for obvious reasons (other than to guarantee my workmanship in doing the conversion itself). However, if I fit a reconditioned engine supplied by the customer from another engine rebuilder, then their own warranty conditions will apply. I will happily liaise with the supplier to ensure these conditions are complied with, but the liability for the warranty will remain with them.