well you are not alone , I removed my engine on my bis this week to replace seals , check clutch etc. I took the flywheel off, when I went to refit I did have the presence of mind to think , hey this must go on a certain way due to the four big holes drilled out of it on one side, having stripped one engine down completely in the past I knew the big end has a massive weight on it so I knew this must mean it should go on in one way only. straight away I knew I should have marked the position when I removed it !! doh
but using the search on here for previous posts I found this thread , it has answered my question , thanks for the help guys.