I'm going from memory here.
The 88 receiver is rated at around 45kpsi. Original 7.92x57j was around 40kpsi average pressure.
Also, if I recall correctly, the SAAMI spec for any 8mm Mauser is 38.5kpsi. It's based on these older actions.
The Romanian surplus is safe as it stays true to the 1905 spitzer round -- the 7.92x57js. This is what the 88/05 will fire safely as the bullet has a small driving band.
The 198grn 7.92x57jsS is not safe to run through this rifle. Over-proof pressures and large bullet bearing surfaces may cause failures.
I recipe for the 7.92x57js I fire in my 1892 Amberg is 150 grain Hornady 0.323" bullets over 45 grains of Varget. This is a nice, soft shooting load. Check your manuals; like I said, this is going from memory!!! My notes are at the shop!!!
The mainspring from a Gewehr 98 will fit this bolt nicely, and I use the extra-power spring from C&R Surplus.
I once had a source for 0.318" bullets; if you have an non-converted 88, I'll see if I can dig it up again.