Javelindan,
I'd expect I have more experience than anyone else on this planet when it comes to hopping up a 258 in a 69 Javelin, as I've run that combo on the street/strip for about 20 years, with times in the 13'9's.
The cam I use currently is a Crane, with 218/224 @ 0.050, and .494/.512 lift, on 112 degree lobe center. I love it. It idles very well, and with quiet mufflers on it you couldn't tell it isn't stock. With a pair of 2.5" Dynomax mufflers you can hear it lope a bit. It pulls really smooth, and pulls hard up to the 6200 rpm I shift at. If I could improve the cam, I'd add faster ramp rates (the AMC uses a large lifter and can afford a faster ramp than a Chevy) and I'd tighten the lobe center to 111. SOUND FAMILIAR? IT'S THE CAM YOU HAVE!
That cam will give you great street/strip results, easy 14's, and low 13's if you really go after them with the other mods. Keep the compression down to 10:1 or lower - I've run 11.25:1 and the cam just builds too much pressure at low RPM, making it very hard to crank over and start when hot.
Clifford's folks don't know the AMC the way they know other inlines, and who can blame them as almost nobody drag races with one.
I'd skip the large valve conversion - it's really not going to help you (I run stock valve sizes in a 1968 era 199 head). The 4.0L head offers much more.
Chris in KC
