what carborators, make and model go in an alpha romero, 1981, spider
veloce and where can i find a good rebuilt pair for my car

The Alpha Romeo Spider Veloce 1981 does not have a carburetor since
the engine (a 2 liter 1961 cc 120cid 4 cylinder) is a fuel injection
engine

but you can find all the parts for your car here 

https://www.rockauto.com/dbphp/mak,ALFA+ROMEO

injectors cost about 50 dollars a piece and you will need 4

apparently a conversion took place and the injectors were removed and
racing carborators installed which do not work

my personal advice would be to rebuild the injection system

The parts not being original and probably rigged in some form or
fashion may be the reason they do not work

i just spoke with the mechanic who says that it wd be cheaper to
replaced the carb-he took the manifold appart as well-than to replace
the whole fuel injection system which has bee torn appart and is gone