Line honing and bearing clearance

I’m getting main studs for my barra So from what I understand the machine shop will need to line hone the journals that seat the main bearings correct? In order to achieve the correct torque/clearance for the new studs right? In doing so, will I need to change the size of my bearings or keep the stock size?

It will depend on several factors - primarily the material used for the block and main caps/girdle - aluminium will deform more than cast iron, and the distance from the fasteners to the main bearing bores - some are very close and these will distort the block more around the bore than when they're further away.

In your case, from one of the Aussie specialists, Precision Specialists' "Tunnel bore and honing is included in all our Barra builds as the cranks tunnel becomes distorted once better main cap fastening techniques are used. Without this you risk bearing issues.".

However, that may in part be them 'covering their a$$s' in case of a failure - at a minimum, when you've fitted the studs and torqued them, carefully measure the bores for distortion. You may decide it isn't required, but if you do, make sure they're COMPETENT - you don't want to swap a minor problem for a bigger one..

Normal practice for the line bore is to remove a small amount of material from the caps/girdle, and sometimes the block - 1-2 thou', just enough to have virgin material. However, some bearing manufacturers will offer oversized (the outside diameter) bearings which avoid the need to skim the caps or block, and they're also very handy for correcting insufficient crush in the mains - I don't have any specific recommendation, though...

As you're in the 'States, this may be of interest, as it has some 'domestic' suppliers at the end - https://www.enginelabs.com/engine-tech/an-australian-in-the-states-building-a-ford-barra-in-the-u-s/