Which intake should I use/ buy

3.90 gears are available for your 8-1/4 for a couple hundred bucks plus setup.....itll ruin your gas mileage if you care about such things and the car will be a blast to drive and drag.
Dont forget to do a proper tuneup and put some water in that radiator lol.
really dont want to spend money on the rearend as ive thought about mini tubbing it with an 8.8 that i already have its 373 gears and is 56.5 wide compared to 57 1/8. and i still have small bolt pattern on the rear and axels for big are expensive also the 8.8 is posi and ,y current isn't