whats your plans for the truck? any power adders? and modifications to make it faster?
if its gonna stay stock, get a servo and shift kit for the 60e and a deep ptranny pan and tranny cooler, it will hold up just fine, maybe not for ever but for awhile, anyway long enough to save money for a built tranny

youre in NO power band for a 4l80e swap, i have almost 500 rwhp going through my 60E and havent had a single issue, it was built by performabuilt, FLT is a sponser here i would talk to them about a built tranny when the time comes.