It’s the other way around - the early FE’s had the single piece fuel pump eccentric thru ‘73, then starting ‘74 model year it switched to the two piece eccentric.
The Ford part number for the single piece FE fuel pump eccentric is C3AZ-6287-A. It’s long discontinued from Ford but there are NOS ones out there, and used ones on eBay.
Yes it was Barry Rabotnick’s book that recommended the modern Ford Motorsports substitution. Although Barry called it a 460 eccentric in his book, Ford Motorsports lists it as for the small block 289/302/351W, but it’s the version with the 7/16” bolt hole. It’s part number M-6287-C302. Be careful not to order the version with the 3/8” bolt hole. The Motorsports one is theoretically still available, although I don’t know if there are any supply chain issues at the moment. it’s generally more cost friendly new than the used FE ones on eBay.