Your post lacks a good description about the nitrous kit so it is hard to answer.
I am guessing that you have a square flange Holley type N2O plate & are trying to put it on a Q-jet spread bore manifold????
If so, I do not recommend it as any spacers/adapters between the manifold & N2O plate may cause mixture problems & potentially harm the engine. Nitrous is safe if used properly, but destructive when used improperly.
I'm sure you could find a used spread bore plate cheaply as they are only around $125 new.