Do you have a wiper motor that is set up to work inside the smoothed firewall?
You can definitely fit a 6.4 with variable length intake runners with the flat firewall and no wiper motor in the engine bay.
I have a wiper motor from a Dakota mounted on the inside. I was shocked at how easy the conversion was. The arm off the motor was the proper length so I didn't have to do any calculations to get the ratios correct. I also figured out the wiring so I could use my stock wiper switch. It's still a 2 speed, but the slow speed is faster than the stock fast speed.
One regret I have is not cutting the cowl louvers out and smoothing them over. There's no need for them at all. I do have the holes inside sealed.
Thanks for the extra pictures. I really like what you did. One of the major things that bugged me about the G3 swap was the darn remote oil filter. Now the only thing to figure out next is the AC compressor. I'd like to use the stock car pulley configuration, but I believe the stock AC compressor interferes with the TTI mount and maybe the K-member. I guess worse case is I use the mini compressor I have now and make a bracket.