Just a point of interest. You mention 'some old Rhodesian teak', treasure it because there is no more 'new' Rhodesian teak. It was used for railway sleepers initially. Since converted to concrete sleepers and Rhodesian teak is no longer available except in old sleepers and parque flooring.
what roof covering do you have. Your trusses look like the type designed for tiles. If you've got e.g. metal sheeting for roofing you would have some leeway with the number of supports needed in the trusses
Is it a Transit? Restored a 1972 MK1 with lot lot of help from the Brit Transi forum. Took 5 years and then got an offer I couldn't refuse - regrets ever since.
Agree. Most good varnishes have 50%+ oil content to 'feed' the timber, and a 'shelac' to seal the oil in.
The 'shelac' breaks down in time, with exposure to UV, making life easier for a light sanding and reapply of varnish.
Idle but won't rev - runs rough = all of the aforementioned, but very possibly a silencer clogged with carbon. Too much oil in the fuel mix, faulty spark or other poor ignition will deposit gunk in the silencer which interupts the free flow of exhaust air. Remove, clean thoroughly and reassemble.