As Ramon says the benson that I Linked to earlier was a JB Weld Job.
There are a couple of downsides to the bolt together sandwich one is that you need a relatively thick cylinder wall to get enough depth of thread and a suitable flat surface. The other is that if you use the same studs through the lot then when you take the chest cover off to adjust the valve everything else starts to move. Its better to have a set of CSK fixings holding the chest and port blocks in place and the chest cover studs on a different hole spacing.
Impressive examples of fabricated parts in the previous posts !
have a look here
this fellow have a plan to download for a two cylinder engine with detailled fabrication (by brazing) of sub assemblies : cylinder block, stands etc... This engine looks very similar to the one you show. You may easily enlarge the drawings if you think it is too small. http://jean-luc.soumard.pagesperso-orange.fr/