I'm building a turbo pinto. its going to be a blow through system, but im not sure what carbys to run. By the way the head has been ported, runing a mild cam and a t28 turbo with 7psi, standard bottom end. these are my options
 
Single 45 sidedraft
twin 40 sidedrafts
32/36 downdraft.
 
 

I know a single 45mm weber works. With one side blocked off.

so one side was blocked off for a reason?

none of them go efi it's too easy these days, have you thought about the fuel system and how the pressure will have to rise inline with boost, then something to retard the timing under boost, those things add up and can easily end up more than a cheap efi setup,
 
i dunno about blocking one side of the sidedraft carby it wouldn't work on those off the shelf manifolds

what about draw or suck through system? What are the pos and neg with that?

If you really want to go carby blow through I would use a Holley, cheaper and easier to modify.  Plus once you realise how much better efi is you would have wasted minimal money and little time.  Most carby setups are not daily drivers or street driven often.
 
I would not go draw through because that instantly rules out an intercooler, plus the turbo requires different oil seals.
 
You should be able to do some form of ign retard with the std vac can on your dissy because they're dual ported on both sides.

well this is my first engine build. so i guess i will have to start somewhere lol
 

why not just get it running with the std 32/36 and a distributor then look at running the ignition from an ecu, then change over the fuel, then add the turbo in 3 stages , it's probably a bit much for a first engine to be turbo'd
 

Solex or SU carby. single 52mm would be ok. Maybe look into a motorbike carbie may work better if you have the time to fiddle to get it right.
Of look into straight gas with a gas reserch TB. This would be far beter than a carb suck or blow thru set up IMO.

+1 straight gas.
Eliminate a couple of intake temp and compression issues straight up.