Hello fellow Lister enthusiasts, I have been a lurker on this forum for many years, and this thread has prompted me to finally join up.
The OP could try a contact I have found in the UK, the following details were taken from an open forum:
I have for sale various parts from Lister FR4 engines (1 marine and 1 industrial). Blackstone 3G gearbox in pieces. These came as a job lot when I was looking for a FR4 industrial - still looking and could swap for a running FR4 marine.
Mike 01453 549105
With the exception of the exhaust manifold, I think that he would have most of the parts you require, as the FR2 and FR4 have many interchagable parts.