I have this cam in my 68' 340 yellow dart and have yet to race it at the track, But it runs great on the street so far.
My combo is made up of old left over parts from other peoples projects that never got finished and I bought, and I did not want to get rid off the stuff years later, and so I am building this 68 dart 340 just for fun.

I am using this cam with matched springs, etc the original X heads,& 340 block, .030 trw forged 12 1/2 to 1's, 727 with 4200 stall, hooker headers,& full flowmaster 40's exhaust with factory exhaust tips, 8 3/4 rear with 3.91. Holley strip dominator intake and 780 holley vac.sec....
This is a car of mine that will sit parked more than it is driven as I have the blower car and my GSS's to play with too.

I am curious what the dart will do, but plan to race it as soon as we can at orlando speedworld ( my closest track)

I have used the 557 profile in my big block 440 demon 340 car also for awhile before switching to a roller cammed blown race motor and went a best of 11.30 et with the 557 cam and 11:1 comp ratio.
I attatched a pic, hope it comes thru...
Grant Eaton 407-947-9005