Either if your looking for it to be a daily driver, or to make more power, you should go with the MHG if you have to do a head gasket job. That's my opinion. If you have to do it, do it right the first time. And if it were me I would go ahead and rebuild the engine while its out. It will be alot cheaper to do it at that point then later on down the road. And after that you know your ready for some good power as long as it is a good shop that's done the work. Also, just because they say they have worked on supra's before doesn't mean they will necessarily do it right. Believe me, I know
I had a shop completely build a 7mgte for me, the guy said he had worked on many supra's before. I trusted him, that motor turned out to be a complete failure in many ways. As for the 2j swap being near the same price,, that's completely wrong. Even if you were to do the swap yourself it would still cost a decent amount more than rebuilding the 7M. However, if you do have the extra cash I would say go for the swap. The 7M is a great motor, but if you have the money and the option to do so I would say do the 2j swap as you will most likely be happier in the long run.
Either way, just ensure your choice is carried out properly and you will be happy with it! Good luck!