The seattube is 28.6mm od.
The toptube is 25.4mm od.
I have some 28.6mm id cromo tubing that'd slip right over the remnants of the seattube after I cut the seized bit out and I could shim it down to 27.2mm to fit a nice post in.
Trouble is that that tubing is 31.8mm od so it wouldn't sit nicely into the remnants of the seat lug a'la @Hulsroy one.
I could get a whole new seat lug but so far I can't find one for a 31.8mm seattube and a 25.4mm top tube.
I could sleeve the toptube and then fit an oversized lug but with a fairly slender 25.4mm toptube I think this could look a bit clumsy.
I think the better option might be to cut most of the seat lug away, creating a 31.8mm mitre on the end of the toptube with the remnants of the seat lug acting as reinforcement and do a fillet braze to the new seat tube.
Doing it that way might, I think, make removing the seized post a bit easier too.
So doing some measuring of the Holdsworth.
The seattube is 28.6mm od.
The toptube is 25.4mm od.
I have some 28.6mm id cromo tubing that'd slip right over the remnants of the seattube after I cut the seized bit out and I could shim it down to 27.2mm to fit a nice post in.
Trouble is that that tubing is 31.8mm od so it wouldn't sit nicely into the remnants of the seat lug a'la @Hulsroy one.
I could get a whole new seat lug but so far I can't find one for a 31.8mm seattube and a 25.4mm top tube.
I could sleeve the toptube and then fit an oversized lug but with a fairly slender 25.4mm toptube I think this could look a bit clumsy.
I think the better option might be to cut most of the seat lug away, creating a 31.8mm mitre on the end of the toptube with the remnants of the seat lug acting as reinforcement and do a fillet braze to the new seat tube.
Doing it that way might, I think, make removing the seized post a bit easier too.