john rc
most of the reading I have done suggest's that any wing with an area of roughly 1000 squar inches will be o.k.
otherwise the wing loading gets too high and you get exsessive landing speeds and other problems .
also if i'm not mistaken the mac. is already on the heavy side .you would need a bigger plane than .60 size to accomadate the extra weight of a conversion engine .
weigh your .60 engine aand your conversion candidate and compare alittle heavy (a few ounces)you may be ok
beyond that your pushing your luck.