I'm not the best at freehand sketching but here goes..
My subframe intentions...
Inspiration taken from some of the MR2 Underbraces you see floating around...
(A) - are the engine mounting points
(B) - are the gearbox mounting points
(C) - will be a pair of new points on each side chassis rail
(D) - will bolt to the front crossmember between engine bay and fuel tank
(E) - will be a modded rev1 subframe
Hope that explains it better :)
Using the engine as a streesed member is a viable alternative but only if it's rigid mounted. I'd prefer to keep some comfort with it :)