8's and 11's have different size bases and different mounting bolt distances. Most Ariens chassis come predrilled for 8's and 11's as the same base is used in several hp models so the 11 can be mounted and the pulley distance front to back should lign up.
The 11 crank will sit higher so a longer belt would be needed. The 924 is a generic designation and applies to many models which have various arrangements of chute crank and it's supports. For example, 924's chute mounted cranks with L-head engines would not be a direct match for an OHV Honda. There's no headbolts on top on an OHV like an L-head. If your's has the chute gear supported off the head and you want to put an OHV on there you would have to come up with a support mechanism. If you put a higher (11hp) L-head on there you'll have to mouse the chute mechanism hight. The rod will not go directly to the linkup on the back of the chute. That's guessing you have a chute mounted mechanism.
I'm not positive about all 924's but possibly some came with crank arrangements like on the 924050 i.e. at the side under the carb. There's just enough room to fit a Honda 6.5hp but slight mod's needed for an 11 OHV. A new support bracket has to be made up.
Generally unless you have the means for metalworking brackets it's best to stick with a direct replacement engine on most of the newer Ariens machines, roughly late 90's forward. Earlier bodies are much easier because of the chute crank arrangement to the side - not on the back of the chute.
