i just put a 308 on botht he 250 and 360 and it fit the clutch cover no probs, you can aslo use the 275 one but up at the top near the kick starter it has more and you need to snip it and take a little bit out, i remebr i used one on my 360 case when i realised it was too long in that section maybe cut out 5mm and then stuck the 2 end toghether worked fine and all holes lined up.
i suspec the Dt1-2 fit as well and the Rt1-2 i think the issue was the rt3, but dont qote me. they all fit just the 275 prefix needs to be shortend at the kicker which is a 2 sec job. there about $1 on ebay or a full set is $9.95 plus postage.