can i stretch my 12r 14-16 inchs safely

i have an 03 12R want to stretch it out with a new swingarm from trac and bump up the back tire to a 240 or 250. the swingarm goes from 12-16 inches extra. looks great, but will it ride well or is it too long creating to much stress on frame and bar. dont want a show bike. i ride. 
