He's talking out his arse, getting 350+ at 1 bar, on a T34(same as 35) isn't going to happen, why the cut back blades, totally unnecessary on t34/35, BD10 cams are pretty useless, in power gain but do lose you quite a bit, idiotic to replace the exhaust cam anyway at this power level as std BD8 perfectly fine.
Be aware if the 200 block is on last oversize, if anything happens bore wise it is as good as scrap, or EXPENSIVE sorting out, 200 block not needed at this power level either.
1000cc greys ?, maybe his came from a JUMBO JET ?, as the std 0280 150 403, or to cossie people greys are 503cc/min, the number on the end does not denote the cc rating in any way.
Not being funny but take someone with you who knows cossies, as this seller sounds full of shit.
I don't know the place in london who did the engine, but cossie are very easy to do, just make sure if you do drive it give it some shit, then when you stop leave it running whilst chatting to owner whilst fan cuts in then out, see if he gets nervous, the usual ballache with these is the HG popping, a no no word with cossie owners!!
tabetha