my experience may be of interest - had this cross-ram ( 99008.352 ) with 47mm OER on 383 SBC. My valve covers were fine but tall covers would not have cleared. Core shift in the manifold meant port alignment was bad, had to slot manifold holes and still side to side alignment was a compromise.
I could not configure the carbs to deliver enough pump shot to compensate for the long runner design and I would get a lean rattle if I punched the gas unless the main circuits were already flowing well. I went to the trouble of fitting an O2 sensor bung in each primary pipe and really put a lot of effort into synchronisation, tuning idle and progression circuits for best driveability and trimming the WOT curve as best I could) and found that getting seamless transitions required a mixture that was rich steady state.