afore mentioned solid MK1 dogbone mount is known as a "coops" dogbone iirc. Give him a PM about them.
If I were fitting a solid dogbone to a MK2, i'd be worried about the bolt hole where it connects into the gearbox. People have had problems with the poly-bushed dogbones striping threads out where they are mounted to the gearbox. I don't think it's fair to say that this WILL occur on all cars fitted with a stiffer dogbone, but if your fitting a SOLID one......that's even more stress.
On a MK1 you don't get that problem because of the much better way in which the dogbone connects to the gearbox. (MK1 FTFW
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As for the extra stress put on the other 2 engine mounts, I'd imagine there would be some, but nothing to really worry about. Just keep an eye on them.
So to summarise, sell up and buy a MK1!