Stick with what you have if it's rated a to 207 hp net (154 kW) like I think it is. Check my posts on the XE I have. I've never had a lean backfire with my CA300 432 CFM carb, and it's got perfect chamber filling with the adaptor I have. On a silly twin-throat Weber intake, no less.
The issue for me is the cost of the potentially better GRA carb. The CA 225 (207 hp max) and CA300 (216 or 270 hp, 161 or 201 kW), and CA 425 Impco carbs (287 HP, 214 Kw) are better as stock replacement carbs on sixes and V8's, with a lot more work required to get them running well in a hot six cylinder car due to there inability to cope with big cams and poor vacuum off idle. The GRA carbs are much more adjustable when you buy the Century converter they have to run with. So swapping the whole set up is not a cheap proposition when your already running an L or E -convertor.
There are some other matters. A single GRA carb is not well placed on the stock Cain/Redline or 34 ADM 2-barrel intake manifold with an XF carby engine. The flow is biased because of the sharp 90 degree bend. This is not a good idea. Secondly, the EFI Falcon plenumb, even with its nice long runners and even though its often much better than the silly idea of putting a CA 425 four feet from the intake valves like on dual fuel XE/XF LPG engines...the GRA carb is not a good prospect. The after market need to work on some rat roaster intake manifolds like the Z/28 Cross Ram and 262 V6 Bowtie manifolds, reworked for the in-line sixes. It' s beyond the blokes that build them at the moment, they've got bigger fish to fry.
The Gas Research carbs are the best thing around, and will grow and grow in popularity, especially with the street machine set who don't like wall to wall electronics. The rack and pinion system, and the ability to run two carbs phased to perfection, is well up on any thing Impco can do at the moment. They have no electronic idle assistance or any interface units yet, but they surely will soon. And when some figures out how to make them work in dual fuel set-ups, they'll sell like hot cakes!
