I  have a tr1 engined wasp sidecar the engine is currently apart for a gearbox issue.Before it gets reassembled which mods are considered better ,it currently uses 40 mm dellorto carbs.Either 750 heads on the tr1 bottom end or 1100 crank/cylinder/heads on the tr1 bottom end?

1100 crank /cylinder/but 750 heads , don´t use  the TR heads, make sense with TR1 bottom end, more Torque but not much  more power on higher revs. For best results use BT 1100 Crank,  special Pistons with a Dome for more compression and  different camshaft , but that is a more expensive  conversion, and not plug and play. 40 Dellortos  are a good decision on any configuration,
Ali