Ok, got the engine running now after a top end decoke and valve relap. Sounded good yesterday.
So onto the forks and brakes.
I drained the fork oil, it was black, getting nearly 500ml from the 2 legs.
Question is how much should I put back? The V35 manual says 0.070 Litres but those forks are much shorter, is there a head space dimension to measure at the top that would indicate the fork is correctly filled?
the 500ml of black is probably oil and muck not much oil. My v50 spat out lots of mayo and gunge when i drained the forks
i dont have any specs for the v35tt but 0.07l is correct for a normal v35/50
I did not notice much difference with forks when my v35 was parked next to a v35tt, its only for basic lube and wont effect the handling I would be tempted to go with 0.07l per leg and see how you get on
only doc i could find was a link to the v35ntx
http://www.thisoldtractor.com/mg_manuals/workshop_manual_350-ntx_650-ntx_it.pdf
Thanks for that V35 
 I’d not seen the NTX manual before and although its a poor quality scan it looks like 460ml per leg, which would line up better with what came out.
On the subject of fork oil, I am rebuilding a Monza and the manual says to use ATF in the forks. I have half a bottle of SAE10 fork oil, can I use that instead?
Its just lubricant, it does not have any effect on the damping
.
Should be ok but price of atf is under £10 a litre