OK, sure, but then you won't get that with a 437 either.
In so many scenarios, RAM = power, so you could leverage your existing software + experience by a redesign of your board which has some RAM chips on it, a few MB. Beyond that, yeah, you need a faster CPU and then you have to redesign most of your board, and much software. RAM is a central issue in many microcontroller projects, and one tends to have far too little of it on-chip. And if you have it off-chip you lose much of your GPIO.
OTOH one can get really clever with graphics. I've done some impressive graphics with a Z80 at 8MHz, DMA, dual video RAMs, a graphics controller (9367, later UPD7220)... Lots of potential for tricks. But again you may need RAM.