Hi guys. I was wondering if someone can tell me the biggest cam that will fit in a stock 1969 383. Already have a 3500 stall converter 410 gears, Headers with 3" exhaust and a torker intake with an 850 cfm carb. Thanks.

Not the biggest cam but I’ve had good luck with a .484 Direct Connection hydraulic in my 68 383 Coronet. With basically the same intake, carb, converter and gears as you have I’ve run 12.50s with slicks and open headers. Some people run bigger cams but with stock iron heads that cam works good. Give Jim at Racer Brown a call 410-866-7660. He knows Mopar cams.

Stay away from the Moparts Purple Shaft Street Hemi grinds They are junk and sound good but don't make as much power or run as good at the track as some of the better grinds from Bullett, Lunati and Comp Cams do
As long as your motor is stock, has not been blueprinted or rebuilt to NHRA blue print specs you can run some big cams with wide lobe separation angles with lots of lift like the Comp Cam grinds,XE274H,XE284H and their XE294H as well as the higher lift XE275HL and their XE285HL.I would installed them between 106 to 108 on the Intake lobe centers also
After looking at and rereading your post about your car and engine I wouldn't run the bigger XE295HL unless you swap the single plane intake to good dual plane like the Edelrock Performer RPM intakes, they make a hoop more power below 5500 RPM than the old schools 383 Torker and 383 Torker 2 manifolds do
I hope you have good converter also

Contact fast68plymouth here on this forum and let him spec a cam for you.

if the engine is stock then your biggest problems will be piston to valve clearance and retainer to guide/seal clearance. other wise "biggest" won't be big until those issues are addressed.