I would say cut it. It's what you want to do, or else you wouldn't be asking. The world won't stop revolving if you do.
Do that and optimize the suspension and you'll love it.
Just think guys, ''back in the day'' when these cars were new or almost new, nobody worried about matching numbers and production figures, and as a matter of fact, a lot of famous race cars that we all look up to are actually rare cars that were cut up ''back in the day''.
That being said, it is possible to optimize the car without cutting it up, check out the stock eliminator cars and the new F.A.S.T. series.
Perhaps find a car that is less than desirable to cut up for a race car if you want to go that way, only if you have a feeling of future regret about cutting a rare car up. Then sell yours to the resto crowd to finance the build.
That's what i did in my build thread, and i feel good about building a slant 6 car for what i wanted to do ultimately instead of the real L code 360 4 speed car that i still got.......
Truthfully, i'm in a dilemma similar to yours as we speak with a very similar car. (Not my build thread car).
It's your car, your choice.
Just my 2 cents,
Tom.