The bonnet clearance is the usual deal breaker with the LD block. Also, LD blocks are only 84.5mm bore. Overboring only gets you to 86-87mm max, so for really big bore for stuff well above 3.1, the only route is liners. And a custom billet crank with big stroke (85/86mm). V07 crank from an LD28 won't cut it I'm afraid (not without welding, offset grinding, etc. and even then its still a lardy great truck crank). For the vast majority who fantasize about 3.35-3.5 engines, the financial effort to achieve that result is powerfully dissuasive....
Besides, that Datsunworks head that gets mentioned above would give you plenty of kickass sitting on top a comparatively "ordinary" 3.1-3.2L stroker tbh! But you're still talking £££££ cylinder head sitting on a ££££ bottom end.
The above Facebook comments also make me want to bash my head against the wall. Rebello HP fantasy figures and talk of 91 octane (i.e. ubershit street gas)...