For your example, yes, you can combine keywords with any text. These are valid
Lua Code:
## Version: 6.2.@project-revision@ -- prints 6.2.r8 if revision is 8
## Version: @project-revision@-beta
## Version: @project-version@
## Version: @project-revision@ -- prints r8 even if you tag it as beta or release 6.2-beta1
Read the docs on the difference between revisions and versions, if you are unclear.