"were you involved developing the 240Z for racing with the NMC competition department here in the USA"
No. I raced an MG Midget in SCCA F-Production from 1971 to 1974. Then I raced an Alexis Formula Ford in 1976-1978. Before I got my license in 1971, I hung out with a group of guys racing mostly British products and a Brabham FC from around 1967. I was 14. One of the guys who hung with us at the races drove a Fairlady 1600 and later in 1972, another friend started racing a Datsun 1200 in C-Sedan. When his car ran well, it smoked the Mini Coopers. But I digress...
The NMC competition department was nothing more than parts distribution. Datsun Competition Department, Nissan Motor Corporation in the USA distributed parts. The race teams we are discussing (BRE and Sharp) were East coast and West coast supported racing teams under private ownership and contracted to NMC USA directly. There was an amateur support program which paid money for victories and at certain races, the Datsun Competition Department had a support truck with parts. There were parties and beer as I recall.
In about 1966, Lee Wiley, under the direction of Mr. Katayama, set up a parts distribution of Japanese imported competition parts for the SPL-SRL Fairlady Roasters. In 1967, d*** Roberts was placed in charge of the department. Information from the competition department came in the form of bulletins, 10 - 20 pages of part numbers and descriptions and prices sent to Datsun dealers. I have two distribution bulletins; one from "The Auto Works" in Granada Hills, California and another from Bob Sharp Racing in Danbury, Connecticut. Informational bulletins were also issued. I have one here; "U20 Racing Engine Oil Flow Improvement" issue RB-168. It's a three-page description, tools required, parts required, illustrated, step-by-step set of instructions. The Datsun Competition Department Bulletin from May 1, 1971, is my earliest "Datsun Competition Parts Catalog" although it was little more than 30 sheets stapled together. It includes parts for the 240 Z HLS30 both from the Japanese Sports Option Catalog, September 1970, and the standard parts catalog from November 1969. The first bound, published competition parts catalog, the red one, came April 15, 1973. It included Japanese Sports Option parts, standard parts as well as domestic manufactured competition parts. Flywheels, for example, were manufactured by Tilton. There is nothing in any of my literature that mentions the PS30, PS30SB or the S20 engine.