Classic/Antique Car Repair: 56 gmc v8 upgrade (not chevy), j c whitney, chevy motors

Question
Hello Roger, as a retirement project i bought a 56 GMC and installed a 350/combo. unlike Chevy trucks  I had to buy the universal motor and transmission mounts. I am using the hole where the 6 cyl motor mount hooked up to as a centering point and my motor does not look like it's centered. (off about 3 inches) My frame looks o.k. Any suggestions. I'm thinking about taking the motor mount set up out and rechecking it or buying another. Seems i had a rough time jocking it around to bolt it up to the motor. Being my first time with this kind of setup im unsure if this is normal. Years ago i did a 58 chevy p/u v8 conversion and all I had to do was buy the stock v8 motor mounts and a different bellhousing. GMC didn't use chevy motors so things are different..thanks, wayne de mann  

Answer
i do not know about that change over kit but if you say that there is apx. a 3 in diff. i would look out as you will have all kinds of trouble, thare has to be some kit out there that will be a snap to convert, have you tried the co. j.c.whitney as thay carry all kinds of stuff like that good luck