What model # is the hose in the first 2 pics? Looks like Aeroquip?

The title says main bearing failure xxxx..
So , this motor wasnt rod knocking , didnt wipe a rod journal , just lost oil pressure and or getting noisy?
On a low hr motor like that , heat induced issues often will leave darkened areas around the journal or journals in question.
If the rod bearings are noticebly less worn than the mains , you may be looking at a assembly error especially with the new stroker rotating parts that are in the mix . Can happen to anybody. But would definetly put the preoiler on it after its fixed and before it goes back in and make sure everything is right.

The short hose is 1/2 Type A1 fuel line, the other two are hard wall marked with "MSHA IC-84/15" unable to make out the other numbers. I could PM/email the guy I sent them to and get the info.

Im guessing this is a twin application, any problem with the other engine ?? or did you loose them both...........what does your engine builder say happened, like Mike said were all just guessing not seeing any of the parts.

This whole thread and every suggestion is a waste because there is literally no info. You've pulled one main cap. Pull the engines out and take to your engine builder and get a professional diagnosis. Any engine builder that has been around over 30 years didn't stick around that long by giving customers the shaft.

90 hrs run time...the engine builder did his job. I'd let him take a look at it so he can tell you what really went wrong so you can avoid this down the road. There are about 15 things that could contribute and it may become more clear to someone who builds engines for a living.

Good luck

what is wrong with line boring as long as it is on size?in my mind all the housing bore does is crush the bearing,the bearing never moves in the housing so why would it be necessary to hone it if boring with the proper equipment will put it on size?

Think the sizing is better and it make a rounder hole. Over boring.

The Line Hone should follow a Line Bore procedure , The honing makes a truer rounder shaft bore , better surface RMA for heat transfer and is easier to get very close ID tolerances.
We Only Line Bore IF , a Bearing has spun damaging the housing bore , but we do run the hone through them occasionally if the bearings show something , that may
indicate that we have a misalignment in the housing.

I would think after 90 hours , only pulling #1 Main from a Supercharged engine and seeing the overlay just showing the copper . Maybe .0025 is alittle tight , but by no means
constitutes a main bearing failure.

I had the exact same thing happen to me. Built a new 540 with a new block and crank and used the stock 502 mag oil lines and cooler. After 30 hrs noticed some loss in oil pressure. Main bearings looked terrible. Polished the crank, put in some new bearings, upgraded the lines and cooler and now 5 years later it is still running with no issues. Lack of volume combined with high oil temps is not a good thing.