I used a G body clip/sub frame on my 54. A bit of a challenge getting everything right.
Why is the MII you have not good? If it is in the wrong place you can cut the welds and reset it. If it is not the location then you can always buy better control arms/spindles, steering rack, etc to make it work. Cutting it out and going with a subframe seems a bit severe.
As for the 4 link rear. What is wrong? To rough for you? A 4 link should have coil over shocks on it. You can either get softer springs for them or completely replace them with softer units.
Can you be more specific in what the actual problems are with the existing systems? Right now I would have to question the logic of the person telling you to change.
