Depends on how authentic they will make it. Will the guts look like this: Probably not as this is the Mark VII internals Just remove the cabclone IR stuff, midi controller, internal speaker load stuff and many of the relays. You cannot even see the board for the power tubes as it is buried under layers of boards.
I doubt it will look anything like this. Copied this image from a IIC+ DRG that was listed for sale but probably sold. This is almost what the Mark III looked like. Even the Mark IVB had a separate board and hand wired power tube connections. The Preamp board on the Mark IVB had the green solder mask on it. Do not remember the Mark III DRG internals all that much. Been so long since I have seen it.
It should not matter what is inside if the integrity of the preamp design is still intact. Sort of predates the use of solder mask (green boards) I am not too concerned about that anyway. It does not make it sound better or worse. The layout does make a difference though. LDRs are probably replaced with relays. It may be possible to emulate an LDR with resistors and a relay. Not sure they have to go to that length. This is just speculation anyways. I doubt that LDRs made much of a difference unless there was considerable voltage ripple on the LED part in the circuit. I am sure you can still get some of the large capacitors but those too are becoming harder to resource due to changes in chemistry of the electrolytes and plate structures. Polymer electrolytic caps are becoming more popular and have better thermal and voltage ripple characteristics. That is more or less what Mesa is now using in the Mark VII as they are much smaller in size than the large blue caps and those silver ones. That amp rips. I can imagine that the IIC+ Reissue will be decent. However, will it pass the sniff (hearing) test with enthusiast who have the originals? The Mark VII and JP2C do not have the volume 1 (pre gain) control as Mesa decided to use a fixed voltage divider in place of the potentiometer. That applies to the Mark V as well. Same basic lead drive circuit as it has always been since the IIC+ with some minor tweaks here and there. Layouts did change though, then they added in the kitchen sink with the V90, finally drained it with the Mark VII and did a few other interesting moved in its design.
I see the IIC+ reissue may be similar to the JP2C and Mark VII in some ways but with more gain controls (volume 1). pull switches and the like. This will be a cool amp to have even if it has the busy green boards and ribbon cables and not having any LDRs. Too many think the LDR's have something to do with the character of the originals. It may have some effect, won't deny that.
Can't wait to get my hand on one of them. Will be interesting. A step farther back to the Era of Excellence. JP2C for me was one step back to aid in my regrets of selling the Mark III DRG combo. The Mark VII completely eliminated any regrets of what Mesa amps I sold in the past. Still, I should have not sold the Mark III. I hope that the IIC+ reissue takes me back to what I no longer have. However, it adds to another problem, no more room for all of the gear. Ahh. What will be next? reissue of the Road King? Will have to get one of those too if it becomes a reality. For now, I will relish the thought and focus more on what will be in the horizon for the next best thing. IIC+ Reissue. (Not making any claims as I have yet to hear what this thing sounds like and how it will perform, just more of that GAS voice convincing me it will be epic, the other voice in my head that controls the money is saying something else, but I learned to ignore it from time to time.)