Welcome! I can't offer any direct help, but the following may be useful (sorry if I'm teaching Granny!):
Glass: Windscreens are available from Uroglas (see windscreen thread - just had one fitted and it was perfect); side glass is flat so if none available, it should be possible to get them made at sensible cost; rear screen is a problem, unless someone with a spare is willing to part with it or you are happy with perspex.
Engine/gearbox: same as TR3A and has lots of similarities with TR2-4A generally so I'd suggest joining the TR Register if you haven't already to widen your search.
Body parts: There was something in the last TRAction magazine about new Peerless body parts - Jon Nolan will know more about that. (Jon where are you?)
In reply to your request for body parts, we have complete moulds for a Peerless, and would be happy to supply any you need at a reasonable price. Please e-mail us on epona@hotmail.co.uk or ring 01440786325 or 01440786869, or 07980806752 (Ian) or 07785574564 (Celia). We will be taking our racing Peerless to malvern if you are coming and would be pleased to talk to you there as well .