Many of the European manufacturers ,and frame-builders tended to stick with one standard rake throughout a range of frames.. for road-racing often in recent years this has been around 40/42 mms, except for the quite small frames eg 47/48/49 cms (when indeed they made them) for which 45 mms might be used. I don't think the rake/ trail problem will kick in too much here unless , say a fork for a 58 frame is to be cut back for a 49/.50/51 frame. TVT the manufacturer of that remarkable composite frame in the late 80s/early 90s ( I know this is NOT the List's period./ but it's only used as an example..sorry) used the same head angle for all its frames from 50 to 62cms..and the same fork rake
The problem ogf getting rid of the chrome isn't so much of a problem either...blasting is tedious often. Just take the offending fork down to your local (what a laugh that is in the UK) and ask them to de-chrome it. It's simply a case of reversing the polarity in the vat..or so my chromer tells me. And it's very quick and effective..nom danger at all on thick walls such as a sterring column.
As for threading the plain column, that poses more of a problem in my experience. No matter what make of die I have used and whose die-holder , including all those adjustable ones, I have nearly always finished up with quite a tight thread.. When the columns are made in the factory, the threads are not cut, they are rolled and that process seems able to produce a n accurate thread that is almost unachievable by hand.
The final comment I would make refers to the problem of ensuring that the handlebar stem will actually fit adequately inside the new column. All columns have a constant external diameter, but the internal diameter varies from the bottom upwards. Throughout the Columbus range of tubes,,and assuming that the Guerciotti is made of Columbus.. the gauge of the steerer reduces from 2.3mm to 1.5mm Assuming that Guerciotti has also used the correct size tube set..eg A, B, C etc together with the correct steering column, and assuming that the column has been cut to length by removing excess thread rather than cutting the thicker lower end, with its internal helical reinforcement ribs.. then if the fork column were to be reduced dramatically as opposed to slightly in its length, then it might not be possible to lower the quill of the handlebar stem sufficiently before it struck against the wider diameter reinforced area of the steerer. In such a case it would be necessary to cut the steerer over-length and place a spacer piece within the headset to raise the quill beyond the "narrows" Alternatively.. assuming sufficient column length. one of those awful A-Head type stems could be used with the appropriate headset.
That's quite a depressing note to end on.
Norris Lockley.. thinking about the current plague of micro frames with A-Head stems mounted above 2" spacers and still sloping up at 45 degrees..Settle UK