Hey Worthing, me and a mate are in the middle of restoring a 2005 XStar, we have the GM 5.7 engine, but very similar to yours. When we stripped our downs it looked not too dissimilar to yours inside. We purchased a new engine from Michigan Motorz in the US, cost $2,300 or so. We also purchased an electrical pack, with new distributor, coil and HT leads. Shipping and taxes was about £800 on top. Way cheaper than from the UK, plus we now have a brand new long block with zero hours.
'92 190 Prostar 260hp Indmar.