Rare Holley?

[Mr70]

Holley date codes used three digit from 1965-72.
Four digit from 1973-up.

Purs
Your Holley 4296 was used on ALL the 1969 cars with 427/430HP:
*Corvette ZL-1
*Corvette L-88
*Camaro ZL-1
It was a special application,and should have mechanical secondaries,no choke provision,& double accelerator pump.

There was a Production slowdown for the New 1970 Camaro & Corvette,so they continued to produce the 1969 Camaro & Corvette later into the 1970 Model year,Debuting Mid February-March 1970.
I am not up on the ZL-1 & L-88 timelines,but
I think your Carbs date (Feb.70,1st week),could have been an Assembly line carb.for these HP cars,and not a Service Replacement,if they were indeed built in that time frame.
Rick