I got crowers for my 292. $1100, 6 weeks. But in the long term that's only 600 extra bucks in an 8 grand build, so don't really worry about the cost. I think if you keep your rpms below 6k, your hp in the 500's, your rpms down, and do a lot of balancing, polishing and use good bolts, and keep your rpms down, and use a conservative tune, and keep your rpms down, you could get by with stock rods. But, if you don't open the hood, no one will know it's a 4200 and not a 292. I am a disciple of cylinder head flow. It makes the world go round. And the crankshaft.

"The first rule of overkill: You can never have too much overkill."
"Overkill is underrated."