Help! Source for Bolt Heads?

[Sunray]

"...My No-Go (Field)..." There's a No-Go and a Field. Ain't the same thing.
"...the chamber is nearly 1/8" (.125") longer..." Chamber length means nothing to a rimmed cartridge.
"...the Canadian military doesn't..." CF weapons techs didn't use a Field. Mind you, few CF weapons techs have touched any Lee-Enfield for 20ish years. Only the Techs supporting the Canadian Rangers ever see 'em now. Real firearms are not used by CF Army Cadets any more.
What number do you have now? Gunparts lists stripped 0's and 1's at $12.90US each. Marstar lists 0's, 1's and2's. You'll need a No-Go guage and a Field to check the headspace.