With several existing 2SW postings about Swingarm conversions here, I added some additional measurements to the TZ750 Swingarm in the For Sale section (the Arm is also listed on eBay) in response to a specific question about RD fitment. It looks fairly straightforward since the arm is the same width at the frame end on all RD/R5/DS7's. Note: the RD400 arm is about 1-1/2" longer than the 250/350:
2strokeworld.net/forum/index.php?topic=7811.0 (https://www.2strokeworld.net/forum/index.php?topic=7811.0)
The 750 arm easily handles 200hp, is totally stout, and has needle bearings instead of bushings. If I'm off on some of the RD measurements please shoot me down as I don't have physical examples to get in-person dimensions.
Thanks,
Warren