sheared bolt in block

[Griffer]

Whilst doing the front nearside suspension noticed the front engine mount bracket to block bolt missing, looked closer and its sheared off.
This must have happened a long time ago judging by the amount of corosion present, I've had the car since 99 but obviously never noticed it before. The mount rubber appears to be in good condition, reckon they were changed before I purchased and thats when it sheared.
Tried jacking the engine and no visible movement so the rear bolt must be very tight, obviously though it will have to be done now that I know about it.
Looks like access with the engine in is going to be a swine, anybody know what the bolt length/thread depth may be please assuming I can get in to drill?
Steve

[Boosted Ls1]

Not absolutley certain but iirc it's about 20mm.

Boosted.

[NicBowman]

Hi, I am a bit like you, no stone unturned. But, thinking rationally, if it has been okay for 6 years, I wouldn't panic. I am sure you will do it anyway, good luck.

Nic