Upgrading to dual 28Pict carbs on a 1300 soon, got a few questions

Going to use 20mm tubing very similar to the size of the OG manifold, is it any benefit to go a little bit larger?

I have some 1500 heads, will these plug straight onto the 1300? i have a whole 1500 but i want to keep the 1300..... will this benefit me?

IS basic porting IE unshrouding the valves, match porting to intake and exhaust going to be of any real benefit or just a waste?

Lastly, a Repro Abarth exhaust? worth the money? or shoudl i leave stock muffler on ? ( also have a stockie that hasthe holes in the internals opened up will that be better?)

any other tips for me ?

no keep the manifold the same size as it will give good torque

use the 1500 heads as they have bigger valves.

use the arbath.

allright, sweet, going to fab up those manifolds today and tomorrow dave, then rebuild my carb....... then ill bring it all over and see you with the carbs and we can work out the linkage, if you could work out what it would take to fab it up for me we can get straight on it?

cheers
adam