If you start paying for work to be done by a third party, you might as well get the FD hanger removed, rear brake bridge sorted, welds smoothed, headtube changed to tapered, etc... Then you have smashed £300-£400 so you might as well buy a used aero track frame.
Fire up solidworks!! was thinking the same but can't be bothered to start mine
I understand the budget is tight but can't you just spend £10 in aluminium dropout and pay £40 for a welder to do it? Much easier/faster/safer.