The widebodies are built on the same pan, so no, they are not wider. If the linked car has seats like you want, then they will fit- that's a pan-based car.
FWIW, the "comfort" seats in Vintage/JPS speedsters that everybody keeps recommending are anything but comfortable. The standard "speedster-style" buckets with the holes in the back are much better to me.
The bottom line is: you have to be comfortable in your car, or you won't drive it. I ended up paying a LOT for a set of Fibersteel speedster buckets (he's got them in 3 widths) with injection molded foam pads. I'm 100% comfortable and have the look I want, but have more in seats than some guys do in engines. It was worth it to me, as I can drive the car for long distances with minimal comfort issues.