15hp block repair, Engine shop drilled right through cylinder head bolt holes

Hi all, I removed a 1978 powerhead with two broken head bolts and took it to an Engine rebuild shop. They removed them and inserted helicoils but in the process drilled right through to the other side. Well I didn't expect that!

When looking at the engine from the back, where the head is, the bottom port side cylinder head hole needed the snapped bolt drilled out and the middle bolt hole on the starboard side. The bottom port side hole has been drilled through and has exposed the bottom screw from the bypass cover, as shown in the first picture. I have run a yellow wire through the hole as well.

In the second picture, the starboard middle bolt has been drilled right through to the exhaust cavity where the cylinder port holes are as the yellow wire shows.

So, for those here with more experience , is the middle bolt hole still ok even though it's been drilled through?
Can the other side of the bottom port hole be successfully plugged up with JB Weld/

Hoping the members that know this 15/9.9hp block well can guide me thanks!

Many of these motors were built.----Many good used blocks are available.----E-bay is one place to look.

racerone said:

Many of these motors were built.----Many good used blocks are available.----E-bay is one place to look.

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Good point Racerone, you're one person I've learnt so much from already.
Do you think I can block off the lower left bolt hole drill through they did, as I feel from studying the middle starboard bolt hole that's going through it shouldn't affect it, once the head bolt goes in?
I still can't believe they did that!

Used blocks are easy to find.----If in Canada---evinrudeparts.ca ----May be of help.

Snapper Fisho said:

Good point Racerone, you're one person I've learnt so much from already.
Do you think I can block off the lower left bolt hole drill through they did, as I feel from studying the middle starboard bolt hole that's going through it shouldn't affect it, once the head bolt goes in?
I still can't believe they did that!

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Do the threads go all the way through?

Goop the bolt threads up with a heavy coat of Permatex #1 Form-A-Gasket

I'm in Australia where parts of these are a but harder to source but do come up now and again. Thanks

flyingscott said:

Do the threads go all the way through?

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Hi flyingscott, yes they do. They tried to say it was like that, going all the way through when i showed it to them but the lower port one you can clearly see it is fresh from the other side with the extended tap thread!

Now, thankfully I have taken the bypass cover off with no bolts seized and that hole they made is at the base of the lower bolt thread and does not cut into the water circulation passage.

Maybe sealing it with JB Weld will be strong enough?