Simple solution... Use a higher ISO instead. Full frame should be able to do two or three stops higher ISO than micro 4/3 without any image noise problems.

Depth of field may be a bigger concern (and it doesn't actually change when the sensor format is different... but appears to do so because you'll either need longer focal lengths w/FF or will need to move closer with the same focal length... or a bit of both.)

Cdouthitt, you've already done the focal length conversions... So all you need to do is pick a brand and start shopping. (Why should we pick your gear for you?)

Canon and Nikon will give you the largest selection of FF bodies and lenses to use on them.

I'd recommend a lower cost camera with a better selection of lenses... For example:

Canon 6D Mark II (26MP, $1900) or Nikon D750 (24MP, $1800)
for comparison: Canon 5D Mark IV (30MP, $3300), Nikon D810 (36MP, $2800).

Canon 100-400mm II f/4.5-5.6 ($2000) with Canon 1.4X III ($429) or Kenko 1.4X Pro-300 ($140).
or Nikon 200-500mm f/5.6 ($1400) or Nikkor 80-400mm f/4.5-5.6 ($2300) with Nikon 1.4X III ($500, check compatibility) or Kenko 1.4X Pro-300 ($140).

Canon 70-200mm f/2.8 IS USM II ($1950) or Canon 70-200mm f/4 IS USM ($1400 w/tripod mounting ring).
or Nikkor 70-200mm f/2.8 FL VR ($2800) or Nikkor 70-200mm f/4 ($1565 w/tripod mounting ring).

Canon 24-70mm f/2.8 II ($1750) or Canon 24-70mm f/4 IS ($900)
or Nikkor 24-70mm f/2.8 ($1800, non-VR) or Nikkor 24-70mm f/2.8 VR ($2400)

Canon 16-35mm f/2.8 III ($2000) or Canon 16-35mm f/4 IS ($1000) or Canon 11-24mm f/4 ($2700)
or Nikkor 17-35mm f/2.8 ($1950) or Nikkor 16-35mm f/4 VR ($1100) or Nikkor 14-24mm f/2.8 ($1900)

I'll leave it to you to choose among those what will "fit" your budget. Regardless, you'll be carrying around a lot bigger and heavier kit of gear.

There are various third party options, too. I'll leave it to you to explore those and how they compare with OEM lenses on the cameras (which may assure the best performance).

With the exception of the Nikkor 70-200/2.8 FL, the Nikkor telephotos mentioned do not use fluorite. All the Canon telephotos mentioned do use fluorite, which helps with sharpness and reducing chromatic aberrations. Nikon has recently converted many of their telephoto primes to use fluorite (designated by "FL"), but so far only their 70-200 and new 180-400mm f/4 1.4X zooms use it. Canon's used it in most of their telephoto primes and zooms for several decades.

With the wide angle zooms, in particular... f/2.8 or faster is rarely needed by most users. You probably already know, that type lens is more commonly stopped down for maximum depth of field. You can save $, size and weight opting for an f/4 instead. OTOH, if you do much night photography or are a photojournalist, you may want the f/2.8.

Note that the Canon 11-24mm and Nikkor 14-24mm ultrawides both have a protruding (convex) front elements that preclude using a standard filter on them. There are special filter holders available for them, but they add bulk and cost.

Finally, for telephoto work, you might want to consider complementing the FF camera with an APS-C model. Available from both Canon and Nikon, there are various 20, 21 and 24MP APS-C that give you the "effect" of a 1.5X or 1.6X teleconverter, without need for a teleconverter. The cost of some APS-C models isn't very much more than the cost of OEM 1.4X teleconverters.