Hello Hugues
Just to clarify, PVST is a spanning tree protocol that uses CIsco’s ISL trunking encapsulation, and is incompatible with IEEE 802.1Q tagging. PVST+ is an enhancement to PVST that allows it to function over 802.1Q trunks as well. Rapid PVST+ is simply an enhancement to PVST+ that allows for faster convergence.
Now in most recent Cisco platforms you won’t find plain PVST as an option unless you have a really old switch, and unless you are using ISL trunks (which is unlikely in modern networks), so it would be difficult to achieve this. PVST+ is backward compatible with PVST, so in theory you can have both running, but PVST must run only in an ISL environment. Now PVST+ and Rapid PVST+ essentially are based on STP IEEE802.1D and IEEE 802.1w respectively. Rapid PVST+ is backward compatible with PVST+, and when you require backward compatibility, Rapid PVST+ essentially behaves like PVST+, so it’s as if it doesn’t exist.
So to answer your question, yes it is possible, but PVST can only run in regions of your network using ISL trunks, and Rapid PVST+ will have to operate as PVST+ wherever it encounters it on the network.
I hope this has been helpful!
Laz