it'll need a little work, but woth a grinder, a press, and someone who can tig it, you'll be all set. everyone has thier own way, but this is how i do it. grind the old stem weld off of the bottom of the bottom clamp. do the same for the new 750 clamp. press the stems out. press the 350 stem into the 750. have it re-welded. you can test fit it up to make sure you get it into the clamp all of the way so the nut fits right. this way you have the 350 stem, in the 750 clamps. you only need to order the 350 bearings. or use the old ones. its a little owrk, but not anything you cant manage.
jc