Perhaps...not what you are looking for
but one of the most space constrained engine bays on an A body is the Right hand drive valiant in Australia
Australian headers may be an option
they will get round an automatic trans starter on the LHD, drivers side of the engine,,,but might need rework for the steering box
they are designed to get round a brake booster and a steering box on the LHD narrow passenger side which of course doesn't have the RHD brake booster and steering box crammed in to that space on your car
a chat with pacemaker for just the parts you need may work.
passenger side from one company and drivers side modified or from another company....
not ideal but might work
Products
Castle Auto Electonics (CAE) in australia also used to do a shorty block hugger header kit
this was a flange a set of pipes and a collector flange + collector parts
everything was too long and you adjusted it to fit
tacked it together and then got it professionally welded
can't find the advert anymore but CAE still exists (selling starters, ring gears and FI) and will still have the jig and the ability to make them... they just must not have been a popular line as the whole Castle Auto headers website is currently offline....
an email or a call might result in some parts
www.caeperformanceproducts.com.au - EFI Conversions
Dave