First of all, I find it hard to believe those arrows shoot straight out of a 50# bow, if by "full length" you mean 33". If you cut 3 1/2 inches off that shaft it'll stiffen the spine considerably and you probably won't be able to add enough weight up front to bring it back to where you had it before, but personally I think you'd need to cut close to that much off to spine it properly for your bow. Also, not sure what you mean by "too heavy", as that setup only works out to about 390gr, which is only 7.8gr per pound of draw weight.