engine/tranny angle relative to rear diff.?

[BUXMAN66]

been doing a build up on a '49 gmc 1/2 t. shrtbd 350/350 combo. tranny crossmember (6"drop) from jim carter classic truck parts. got everything finished up 'cept for some last minor details on the engine (hoses,belts...etc.) noticed the angle from the output shaft on trans into the forward u-joint was off.... i placed my magnetic angle finder on my intake (no carb. mounted yet) and my engine was on a 3 deg.negative angle.(below the crank center-line) so in other words my tranny out-put shaft is at a pretty low angle. i can machine some spacers to go between the tranny x-member and the inner frame rail where it bolts at, thus bringing up the out-put shaft angle....but what is the optimum angle needed at the intake/ carb. base ....? thanks for any replies! p.s. it's a real p.i.t.a. undoing other people's screw-up's!! previous owner's "angle iron" tranny x-member nesessitated this whole job. he had a approx. 6" drop from bottom of frame to the tranny mount rubber.....and thus the pinion angle was set for this. hopefully going to a "safe" tubular x-member w/ a 6" drop, i'll still be able to keep the pinion angle the same.