I've looked at the Thumper cam for one of my customers. Honestly, not a fan. It's designed to meet market demand, not to make good power. Plus, it's designed for a 351W, so it's going to be even more lopey on a 289.

I think some good aftermarket 58cc heads and somethign like the Comp Cams XE268H cam would really wake the motor up.

Don't ditch the carb. I run that exact carb on my 331 and it works fine. Once you get your setup ironed out, we can help you get it tuned.

 

actually the thumper cams make a bit more power than the xe cams, BUT since you have stock heads with pressed in studs you can forget about running any cam with more than 480 lift, the performer cam is not a performance cam whatsoever and niether is the performer intake, if you want about 30hp and TQ thats what they will give you. If you want a cam to work with what you have run a comp high energy 260h or if you want lope and a bit more top end the comp 268h, the biggest xe cam you could possibly run would be the xe 262 and that is pushing it on lift.
If you want a good daily driver combo the 260 cam, performer/rpm or stealth intake and a good 600 cfm carb, if you want a bit racier the 268h cam rpm or stealth int and a 600-650 carb with annular boosters.

 

htwheelz: recommendations are based on the fact that he's getting new set of heads (afr165 or TFS).

Starfury seems to be of the same opinion. don't invest money in a new carb. get a set of heads, that xe268h cam and a good dual plane intake (performer rpm, maybe someone has other ideas)

that should do the trick. the bottom end should be able to handle it

 

Thanks guys! Yup your spot on, the heads are going no matter what, so my thought is while the heads are off, why not to it right this time and swap the cam and intake as well...Glad to hear some of you have experience making the 1406 carb work out...I've changed the metering rods and step-up springs a few times and believe I have it dialed in based on the existing application...A buddy of mine seems to think I've over-carbed and with the limited flow of the heads and intake, I'm sure he's right...

Again, I'm not too interested in making her a daily driver, but when I matt it, I want her to respond... Hind-sight is bitch!

 

overcarbing is very easy with a square bore mechanical secondary carb with straight leg boosters, the 1406 is way more tolerant since the front primaries are smaller and the secondaries open on 'demand' being load, rpm etc
but in any case keep the carb for now. you can still swap it if you can't get it right, but i'm quite sure we can help