From what I understand, Yes. I just picked up a 4.1 for $20 from a '84 NA Regal. It had the rolled fillet crank, and 8445 heads.
From the Before Black Website:
http://www.flash.net/~rjgeorge/252V6.htm
GM cars with the Buick 4.1 V6 (252 ci)
(Easily identified from 3.8 Litre by Quadrajet)
80 STD-Electra, OPT-LeSabre
81 STD-Electra, Riviera, OPT-LeSabre, Riviera T Type
82 STD-Electra, Riviera, OPT-LeSabre, Regal Note: Included in Grand National Package
83 STD-Electra, Riviera, OPT-LeSabre, Regal
84 STD-Electra, Riviera, OPT-LeSabre, Regal
Cadillac
81 OPT-All except Limo
82 OPT-Seville, Eldorado, DeVille, Fleetwood
(NOTE: badges will say 4.1 for V6, 4100 for Cad V8)
Oldsmobile
81 STD-98,Toronado
82 STD-98,Toronado
83 STD-98,Toronado
84 STD-Toronado
Pontiac
82 OPT-Bonneville, Grand Prix