International heater boiler specs

Am working on an International Heater boiler model C-100 with a Beckett burner, made pre-1959 sometime. Looking for anyone's experience with these older units, or information about how to locate the manufacturer's specifications for this unit. Specific questing is regarding draft, air setting and OEM nozzle recommendation for this boiler. Also, the unit has a small inspection door in the firebox above the burner. It has a thumb screw that can be adjusted to keep the door open up to 1/2" or so. I would assume that the door should be fully closed when setting the draft and adjusting the air shutter, and during operation in general. Is this correct? Are the typical .04" stack and .01" overfire draft settings appropriate for this unit? Any information is appreciated. Thanks in advance.
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