Re-powering - transmission questions

Hi everyone,
We have placed an order for a new power plant, a Solé Diesel - Mini-74, www.solediesel.com/en-gb/engines/mitsubishi/mini-74.aspx, however I need to choose the correct transmission of course.
Can anyone provide any insight into the Shaft angle? There seems to be several different versions, one with a zero degree shaft angle and another with an 8 degree shaft angle etc.
As well there are several different reduction ratios available, 2:1, 2.47:1, 2.09:1, etc depending on the specific model I choose.
Any help would be appreciated.
thank you