Should be OK, but you will lose a little mileage with no vacuum, and maybe some daily driveability. Otherwise its a great distributor. The cap is bolted to the distributor, so you may have a tough time getting that on and off too since its so close to the firewall.
Im running the 85551 with just mechanical advance on my 496, so its basically the same as yours but less ruggedized, and its just fine.
68 RS/SS 496 T56 6 Speed Tuxedo black w/ white bumblebee. Strange Dana 60, Spicer 3.73 Helical Gears