A stock 0331 flows about the same as a stock Dodge Viper head at the lift Jeep cams typically have, less than .500". I don't think the heads are much of a restriction. I will be mostly cleaning up the casting flaws and the short side radius on mine along with a valve job. $850 doesn't sound like a bad deal for the work done, but the $350 upcharge for a 0331, is getting pricey. You don't need a ton of flow for a 5000 rpm motor. Link to head flow numbers.
http://users.erols.com/srweiss/tablehdc.htm