External transmission corrosion

[Col986]

I have a 2004 986 S which has corrosion on some of the underside components such as the tranny (see attach image).

I'll shortly be replacing the IMSB, so while the tranny is out will try to clean up some of the corrosion. Can I just replace the tranny bolts shown in the pic + other similar on the other side, or do some of them hold internal components of the tranny?

I'm fairly happy with sanding back the steel components & treating with rust preventative such as POR-15, any ideas on what I should use on the tranny itself?

Thanks in advance