is it ok if the pistol shrimp is way bigger than the goby i'm trying to pair him up with

What kind of goby? Do you have pictures of the pistol?

it's a tiger pistol about 2 1/2" and my choices of gobys are a 1 1/2" orange spot prawn, 1" yellow watchman,or a 1/2" twin spot

twin spot gobies are not shrimp gobies (if you mean Signigobius biocellatus). I've had a tiger pistol pair with a Randall's shrimp goby, so that's one choice. The orange-spotted prawn (it is in the same genus as the Randall's) and yellow watchman may be good choices.

yea but i'm concerned with the shrimp is alot bigger than the goby i'll be getting

they should be the same size. i've heard its hard to get shrimp and gobies to pair up anyway.