Really there are only three models of GRiSO. The 850 and 1100 which use the venerable two valve per cylinder motor that was built in various guises since forever and the 1200 four valve per cylinder motor, (Usually referred to as the 8V.) that was produced from 2007 to 2016.
There are virtually no changes to the 2V models during their limited production runs, (2005-2007.) and although there were many detail changes to the 8V models during their time in production the only major change was the swap from the failed flat tappet design to the roller tappets in 2012. That, more than anything else, is the one thing to be aware of, especially in the UK where, amazingly, the problem seems still to be a mystery to many and many more are still in denial.
Congratulations on doing your research before purchase as it will save you both money and heartache down the track. A well sorted GRiSO is a joyous thing. I'll be riding mine as long as I can hold it upright.
Subject: Hello from Staffordshire - England 
Mon Dec 26, 2022 3:05 pm
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will lift the cam covers for you so that you can see that it is a roller tappet model. To show you the difference there are pictures in Beetle's post of Fri May 22, 2020 8:38 in this thread 
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