So most Datsun people know about or have at least looked at Les Collins' L-Series engines, but has anyone had him (or his company) do an A-series?

I have heard of Les Collins, but never seen one his engines.

For the money I would go with PMC Race Engines in Churchill, Vic

Just consider cost vs hp or horses for causes
Les charges an arm and a leg for anything which he can
as what he produces are big hp engines that last.
That is no easy feat and rightly so for the cost.

If you spend 40-50% less you could build your own 16v
mazda b6 head A15 and will make more hp and last longer
than any OHV headed A series.

B6 Miatas crack 160-170hp atw with just top end work and flywheel/clutch.
eg. crazy 2mm shave off the head, custom cams, flywheel clutch,
induction, headers and tune etc..

A 1600cc A15 with the true and tried Miata head mods
bored for stock miata pistons and reworked A series rods
will achieve the same hp as the B6 engine and rev quicker
as the A15 crank is no full counterweighed like the B6.

It will required less rebuilds as well thanks to less
friction for the later belt driven dohc design.

The other choice is boost which would probably cost
the same as the twin cam head but be less reliable
overall and trickier to tune.

Does Steve Newing build engines ??

Does Jeff Taylor still build engines?, he was the best there is for A series.

Steve Newing built his own and won with his own NA engines
he use to source old now illegal lead coated bearings from India
He build the A series for torque not high rpm as they lasted longer
and let him compete with 400cc less capacity than the rest.
He went from A series to his own developed 243hp CA18DE

I still wonder what happened to his stanza coupe it was a beast
even had the alternator running off the rear axle to get more hp