427 TUNNEL PORT
No, NASCAR did'nt ban the 427 TP, they did ban the SOHC, however. Ford teams used the 427 TP quite successfully in 67 and 68 against the MOPAR Hemi's, but it was getting harder for them to do, the Hemi's would run away from the 427 TP's with one carb on board, so NASCAR actually let the Ford teams have the option of using dual 4 barrel carbs (which some of them did), all the while, the MOPAR Hemi's were still using one carb.
It was Ford who pulled the 427 TP's from competition as soon as their racing version of the BOSS 429 was ready. The 427 was no longer competitive against the mighty Hemi, thus it would take a Hemi to beat a Hemi! The BOSS 429 is a Hemi in its valve placement and layout, and just like the MOPAR Hemi, it too can move larger quantities of air/fuel than an FE based wedge head. There were some lesser funded teams that still continued to use the 427 TP up into the 70's, but they just were'nt competitive enough to win anything big.
Combine the BOSS 429 with the sleek new body of the 68/69 Torino and Cyclone, and it was an instant winner....in fact, it was the most winning'est body style in the ratio of wins per season. NASCAR today is very boring, I cant sit and watch a whole race, but I'll watch like say the last 10 laps.