Welcome Jeremy.
1) have a look at Toyo Proxys on Demon Tweeks website, great tyre and excellent value.
2) yes Librands and Harpers, also Heart of England or have one custom made locally (usually cheaper too !!!). Also have a look at this months Miscellany, there's a second hand stainless system for sale at £200, big bore and including manifolds, may be suitable.
3) a few companies do sleeving, a couple advertise in the classic car mags. Trip to W.H.Smith library on Saturday maybe?
Good luck with the recommissioning and keep us all informed!