I am a little late to the party but hope this helps.
My AC Bumpers were bent and knocked and in my car's history file I found an invoice for a set of rear bumpers from around 1980 from a company called Pipecraft owned by the ex racing driver Nick Crossley.
They still exist and are doing well so I took my bumpers over and had new sets made. I got Nick's team to scollop out where the bolts go and finish the pipes with solid sealed ends. All in stainless steel and polished.
They came back perfect and fitted better than the pattern bumpers off my car.
Nick's details are below and a picture of the finished result.
Nick Crossley, M.D.
Pipecraft Innovations Ltd.
(Incorporating Pipecraft Innovations Ltd - CNC Division)
Units 6-7, Wayside,
Commerce Way,
Lancing,
West Sussex. BN15 8SW
Tel: 01903 766778
Fax: 01903 754325
www. pipecraft.co.uk