Yep, there are loads of performance products available for the 289/302. Edelbrocks RPM's Performer (as mentioned before) probably one of the best, for a good combination street/strip combination. Problem is the weight of a 68 model. Probably in the 3200 lbs. range. Someone suggested looking at the Moneymaker. If you will look at the stall ( I think 6000) that baby will spin to the moon. I think Alex said he spins to 10K. To do that, that baby has to be built to the hilt. Also the gearing (I think a 6.52),a street driver it is'nt. But I don't think it was built for that. All business, and all go fast. For a good combo, nice flowing TFS heads, mild but agressive cam, good exhaust you should be able to run in the 13's. On my page I have a 65 coupe with a 302 that ran 12.80's, drove to the track and drove home.
If you are interested its
www.worldaccessnet.com/~harldane/rons1.htm.
And forgive me, a little bragging here from a proud papa...my FB is easy to find...it's the Mustang of the week.
Ron