That's a max effort Pontiac for back in the day.
Lots of people never knew.
Other popular stroker combos for the Pontiac then:
370 out to 448" using a 4-3/16" (4.1875")welded stroker crank
421 out to 482" using a 4-3/8" (4.375") " " "
421 could have gone bigger yet .
The large bore block 3.25" main bearing size ,as always,was there to deal with.
Steel & aluminum rods & forged pistons & cams to go with were also available through:
Ansen Equipment & Forgetrue -pistons
Crankshaft Co. -cranks and steel rods
Howard's - solid roller cams,roller lifters & aluminum rods (Howard's is still in business)
So if you find any of that stuff lying around as new old stock in some forgotten storage or barn ..............?
Any used parts like that were probably punished hard.
Step Away From The KOOL AID !