i agree with sintax, i think the cradle swap should only be done if there is no other way. i made new mounts for my 99-02 250/500. i had them tig welded on, they look very strong but are un tested. i looked at trying to replicate the standard 500 mounts on the 250 frame. the tubing on the 250 is smaller but will work. but the main reason i didnt do was, it would be hard to drill the frame accuratly. i just dont have the equiment to mount and drill a frame so the alternative was a pistol drill and i didnt fancy that. also on the 99-02 frame the space between the cradle tubes is less than the width of the front engine mount on the k5 engine so the alu mount plates would not be straight. i am going to see how the welded mount holds. if it does not i will be going for alu plates and bolts. my frame is away being powder coated, when comes back i will post a pick of the front mount on my thread
regards
john