The Intek arose as a Briggs redesign of the Vanguard (which was a Daihatsu design) to make it cheaper and easier to make. The Vanguard was a successful design, and I believe it is sleeved, but what Briggs did to the Intek I don't know (most likely it's sleeved like the Vanguard). Aside from its remarkable propensity to blow head gaskets, there are two other main distinguishing features of the Intek. First, their air filter doesn't work, and they frequently become dusted early in life. The problem was that the plastic filter box didn't clip together properly, so the filter element was bypassed. Recently Briggs redesigned the filter box. The second problem was the decompressor, as I mentioned in an earlier post in this thread. The tappets need to be adjusted to minimum specified clearance: just 0.0005" more than that is likely to disable the decompressor, with disastrous results (it is a race between the wiring harness and the starter motor for which burns out first, but most tenants don't stop when the first fails, and soldier on until the other burns out as well - a few diehards burn out several starters). So, before you pull the head off, take a close look at the air filter box. It would be worth checking whether you can fit the new revised type. Then, when you put the head back on, adjust the tappets very carefully to minimum spec, then retorque the head and readjust them after a couple of hours running. After that adjust them at least once a year forever, if you want to avoid burned out starter motors.

You may find this previous Outdoorking thread of interest:
https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=39266

In addition to redesigning the air filter box, you will see that Briggs also switched to an electric fuel pump instead of the crankcase-pulse-operated one. I suspect that the pulse one would be fairly satisfactory on an engine with an intact head gasket, but perhaps Briggs' dealers and customers lost patience with the issue (especially if the head gaskets are continuing to fail anyway).