You would probably be better off with the Magnum or ASP 61 as they are so much lighter. Both are bored out 52s. The 80 is probably too heavy for this plane, you'll have all the vertical you want but the flying will probably suffer.

No point going for the OS 70. The ASP 80 is basically a bored out OS 70 copy. So the OS is still too heavy, and now you are paying more.

Visit http://www.skylarkrc.co.uk/ for cheap Saitos and Magnums. Personally I'd try the YS 63. Cheapest I have found is from http://www.probuild-uk.co.uk/.