The use of a lesser vacuum pump as a "forepump" for a higher vacuum system is pretty common. Here's a diagram for how I plumbed mine, just like 4ontheFloor said.

[img]http://pic1.picturetrail.com/VOL137/662484/1080315/33491508.jpg[/img]


1948 3/4-Ton 5-Window Flatbed Chevrolet

34 Years. Now with a '61 261, 848 head, Rochester Monojet carb, SM420 4-speed, 4.10 rear, dual reservoir MC, Bendix up front, 235/85R16 tires, 12-volt w/alternator, electric wipers and a modern radio in the glove box.