Richard, I have an answer but somehow I don't think that it can be this easy, but here goes.
AMT Ertl kit number 31757 is out there now and it has a sprue with the 29 Model A engine in 1/25th scale.
By the way this kit has most of the old Ala Kart sprues from the original release (1962 or so ).
Two newer sources are Revell kit 2348 29 Ford Rat rod. Or the kit 2169 31 A sedan. Most of these kits also have a hopped up engine so there are plenty of unused Stockers. If I am missing the boat here and you want altermarket resin, let me know more. Greg