Link to the Files section of the 2A042 Group:
https://groups.yahoo.com/neo/groups/2A042/files/2A042%20Manuals/ Here's a link to a flying 042 (You see the oil cooler 14 seconds into the VID)...
Notice the alum tube oil cooler loops on the front/top of engine - (an oil cooler is essential) ! ! !
I speculate that he is running a 54x20 prop that has been cut square at the prop tips to be a 50x20...
The prop will need to be 54 or 53 inch dia by 17 inch pitch for the XL... I suggest
http://PerformancePropellersUSA.com or Tennessee and tell them it needs a 1/2 Vw type of profile...
You should see (3300+ rpm static) before you fly...
If you are heavy this will be a very marginal situation and at any weight always a standard day at low elevations...