1st Gen G vans and 61-65 E vans and trucks have doghouses that typically only fit straight engines and appropriate radiators. Seats typically are secured to the floor on the inside mounts via a bent tube leg, which typically is located very close to the doghouse. Add too this that the battery box is usually sandwiched under the driver's seat... modifying the doghouse and floor to accept a V8 is tricky.
If we first remove the seats from the equation, it seems feasible to be able to cleanly modify the doghouse and floor by expanding the width of the opening of the floor and sides. This way, original bolt hole locations will still enable the fastening of the original doghouse sides to bolt to the floor. While resizing the width, it would be easy to add a transmission hump to the rear panel and floor, as well possibly as a fan to evacuate hot air from the doghouse. Does this part make sense so far?
Now let's consider the width of the seats... there is not really any room to expand the width of the doghouse lid due to the width of the two bucket seats. So modifications to the panels would still need to form to the original dimensions of the doghouse lid flange, and it's relative location as original to the van, right?
Let's skip ahead how, and we have a modified doghouse with a V8 stuffed between the frame rails. Now our floor provisions for the seat mounts are likely gone. One method I have seen is the simple attachment of angle iron to the side of the doghouse used as inner seat mounts. However this concerns me, as I don't think that the structure of the doghouse is really designed for the weight of a passenger resting on one side of it. If the factory seat mounts were modified to allow their relocation outboard, I fear they would be flimsy and prone to tilting toward the centreline of the van.
So here I am, throwing the idea out there in hopes that some brave fabricators may take it on! What if the inner seat mounts were made as one unit... the base being like a u-shaped flange (1/4"?) that would line up with the doghouse bolts that wrap around the front (I think the speed nuts in the floor would have to be replaced with welded nuts and the flange in the floor reinforced possibly), and then steel tubing (legs) could extend up from the base and wrap around the doghouse side contours leading up to a plate for mounting the actual seat to? Possibly with a strap (more 1/4" bent around the front of the doghouse?) to add some support to both the drivers and passenger sides? Alternatively, the legs themselves would not have to be curved around the top contour of the doghouse, but rather run straight up and have a sturdy plate that extends inward to the stock seat mounting bolt locations.
Here is idea #2 for seat bases... fabricate a new seat base that instead of having separate floor and wheel well seat brackets, uses a one piece seat bracket that bolts to the original wheel well locations and to the floor bolts on the relocated side of the doghouse. Now that the inner support is moved outboard because of the larger doghouse, tieing it to the wheel well bracket provides lateral support! The top plate structure would be sized to fit the regular seat width requirements, and able to overhang the doghouse width beside the lid. No wrap-around issue. would be easier to remove the side doghouse panel which would only require removing one seat and base at a time...
Oh yeah, the battery box... I think it belongs under the floor.
What are your thoughts? Any fabricators inspired to weigh in on this? Maybe sketch some ideas? Thanks for reading my ramblings!