Cyclocross - Cyclocross crank for older freewheels

I'm building a cyclocross bike on the cheap until I can afford a better drivetrain and already have a Suntour front and rear derailleur and a 6- and 7-speed freewheel hub. I'm looking for a crank and chainwheels and BB to match this set up. (My frame is a Rocky Mountain cyclocross frame from the 90s with an English BB and I have a Suntour bar-end shifters.) I'm assuming none of the newer 8-, 9- and 10-speed cranks will work because of the chain difference. Or is there a place to get chainwheels that fit the newer cranks but work on the older freewheels?

That's the way to do it- frankenbikes rule! Any crank will work with an appropriate chain, but your best performance may be with an older model 8 speed or less. 9 speed chains got narrower, and 9-10 speed (inner only) chainrings were changed accordingly. The outer rings have the same dimensions they always have, although the ramping patterns have changed. That will be a righteous ride-

Thanks for the reply. I guess I'm not quite understanding chains. When I find an 8-speed or lower crank, how do I know which chain to get. Any info on that or referral to sources?