dueceluxe I'm not sure if you ever got an answer to your question, but I'm going to chime in because in 2008 I was in the same boat. We have a 48" BlueStar in a 12' island, with a prep sink located about 48" away, which is where I spend my prep time. Frankly I wish people would focus on answering the direct questions, vs. lecturing about what percentage of prep/cook/cleanup time people "should" be spending in their kitchens, or in which direction they should be facing when doing so. The OP stated they were looking for an island hood for their cooktop, not IF they should be putting the cooktop in the island. For us personally, my prepping and cooking is very intertwined, and we entertain a lot. Ergo, I want to be facing my guests while prepping AND cooking, and not facing my guests during cleanup (THAT sink is behind the prep area against a wall), so the cooktop in the island is what we did and we (and guests) LOVE it and wouldn't go back. It's not for everyone, but it's definitely right for me. Having said all that, yeah, sadly the hood is going to be expensive. We went with a Best by Broan IEX222 51" with a 1500 CFM externally mounted blower. The pros are that the thing will suck up ANYTHING at full speed. The con is that we've had it for 7 years, and unfortunately have gone through 4 control modules or transformers on the thing (everything on it stops working). So nn my frustration I'm now researching replacement hoods, which is going to be $$. It's the price you pay for the style you want. Currently evaluating Cavaliere and Imperial 54" hoods....

You cannot do such a large arch - the overall height of this piece will be approx 18" ( 84 - 18 = 66 ) Do a 2" - 2 1/2" arch on the valance. If you do a column on each side you could then do a crown molding detail that will return on the column and not interfere with the doors of the cabinets. The opening underneath needs to be based on the actual exhaust unit that is required for your range - your appliance folks should be able to help you with that. It will be a challenge since you have a reduced ceiling height and you have an offset vent line ( which needs to be changed - in most areas flex duct is not allowed ). You could also do a chimney style Here are a couple of pictures for short mantles you could create Good luck - I hope you can figure something out!

Given determination of the performance requirements, and selection among hood candidates for cost and aesthetics, then it should be possible to find and download the installation guides for the selected hood and any chimney parts needed. Large hoods will require some help holding it up for fastening. My very large hood required a sheet rock lift to do the hard work holding the hood up while attaching bolts from inside. You will need access to your attic and roof, and if there is room, an in-line silencer will help minimize noise if you use a roof blower. For ideas on hoods and supporting parts, see the Wolf Design Guide (wolfdesignguide.pdf). For silencers, duct clamps and other related devices, see Fantech's web site. I support the jack-of-all-trades suggestion.

I have a Broan. It's a tad noisy but works well and has been reliable. If it has a circuit board I don't what it could possibly be doing. The lights are good. I think it's an Elite E64xxx. (600 cfm 36" hood over a 30" high btu gas range.) I don't like that it has a knob for the light but it's not that bad. Does it click all the boxes for coverage and CFM? Nah, but it's certainly good enough.