A straight-cut close ratio gear set would be a mis-match with a 1098 as I've already said.
You need to understand that a 1098, or over-bored 1098, is a long stroke engine which is capable of providing high torque at mid-range revs, but which can't have a really high-power camshaft and a narrow power band because it can't rev to much over 6000 rpm.
A high-torque engine will have a wide torque band, so a wide ratio gearbox is required, which is what the standard ratio gearbox has.
The straight-cut close ratio box is for competition engines with lots of top-end power within a narrow power band. So a 998, even if bored to 1060 cc, will rev to 7000+ rpm. It can run a 'hot' cam, but a very low final drive ratio is then needed which limits cruising speeds, and a close ratio gearbox to keep it on the cam.
If this is for a road car be careful not to make it unpleasant to drive by either 'over-camming' it or 'under-gearing' it.
The question is what you think SC CR gears will give. On a 1098 you would lose out as the under-gearing would mean could not use the full torque envelope of the engine.
