Main Bearing Bolts - 89 GTA Turbo

Corroded Allen Key Bolt
Quick shout out for some advice on a tool you know works for following ...some of you will have been here for sure...

Three of my main bearing side bolts took a lot of loading and eventually cracked and were removed AOK.. The one under the Aliminium engine plate is clearly corroded such that even slight load is gonna round it...

I have been researching tools to remove but most DIY stuff I wouldnt trust not to snap off making the position worse..

If you have tried something that works let me know...

Thanks
Peter

No special tool but I have had them round the allen and then had to either hammer a torques bit in and also heat with Promax gas.
I'd heat it up first and try with the allen.
I have a few complete old 25turbo engines I'm stripping for spares atm. The are not cross bolt engines but I do have new caphead bolts in stock also.

Slept on it and decided to let my local engineering specialists have a crack at this..
They need to check, polish and balance the crankshaft anyway so seems sensible to leave em to it..
Results including cleaning/blasting the block ready for paint should be known next week..
I'll jump back to projects forum for follow up..
Thanks
Peter