[Gelbster]

The M6 steel bolts -they are going into aluminum alloy - that is the limiting factor, not thread deformation of steel bolts.
The deep sump kit - a few things I did that seem to work:
1. Make sure you install the horizontal baffle in the most effective location relative to the spacer. Above or below - why? In the wrong place the horizontal baffle is relatively ineffective imho. I debated them on this and they eventually conceded by changing their Instructions.
2. Make sure the flaps in the windage walls seal reasonably well.The better kits use s/s flaps with rubber seals because this is an issue on long sweepers.
3. Consider replacing the bolts for the sump plate+2 qt.extender with the correct length s/s studs(EBay). Full thread is O.K.This eliminates the risk of destroying threads in the crankcase halves by over torquing.If you use blue Loctite on the threads into the crankcase ,it works well. Use flange nuts with wicking green Loctite after you do the final torquing.
4.Consider a sump guard/slide
5.Run at least 1 pint lower than max on the dipstick to reduce AOS/overfilling issues
6.Mark your new oil filler cap with the new oil capacity(paint pen) I suggest increasing by only 1 pint because the rear timing chain tensioner always retains almost a pint of old oil. Overfilling at oil change time is easy and has awful results. Much easier to top off after than clean-up the plenums !
Remember that with an extra 2qt./4 pint capacity of the Deep Sump kit, running 1 pint below the max mark on the dipstick is actually immersing the oil pick up in an extra 3 pints of oil compared to stock.Do not over-fill.
I hope this gives you food for thought.