GaPilot is correct, those boats are both Dumas sport 40 class kit builds, the red/white being the U-70/71 Atlas Van Lines and the blue/white being the U-76 Atlas Van Lines kit 1312. Both are now out of production so getting cowl parts for the U-70 will be problematic at best. I went to the Dumas website and found there is nothing listed at all for the U-71 while for the U-76 the plans, instructions and decals appear to be available. These are not usable to build a boat from scratch so it's not really worth the money(in my opinion anyway) to buy them. Both boats appear to be stock builds as the U-76 engine is sitting on a Dumas style engine mounting. As for the rest of the hardware, I would need to see pictures of all of it to tell if it's home made, Dumas or other manufacturer produced. The engines appear to be K&Bs, the marine 40 side exhaust in the U-70, the marine .45 front exhaust with an exhaust throttle on the U-76. If I am right on the manufacturer, both will be problematic on getting replacement parts as well as I discovered when I tried to get parts for my .45.
As far as the field box, can't say anything about that other than it appears to be a home built design and not something that was commercially made. The radio, if a Craft, is probably not legal to use as it's most likely a wide band system which were "outlawed" for the most part back in 1991.
If you would like to see pictures of the full sized U-76 in it's original paint, one of which even shows a very young legendary crewchief named Jim Lucero talking to driver George Henley, here's an address that shows the boat:
http://newtonmarine.smugmug.com/Hydroplanes/1974/11135569_GMNcnF#!i=780330367&k=vnpCp
As for the U-71, it can be seen in this picture:
http://newtonmarine.smugmug.com/Hydroplanes/1972/20646348_ZKTcqb#!i=1636951456&k=rS8TMvt&lb=1&s=A

Just had a thought, if you have plans on racing these two boats, you will need to add drivers to the cockpits or they aren't legal to run in sanctioned regattas. Just thought you should know before going to a race and being told no by the race director