Rebuild v8250 using another motors top end

I can’t find an engine in Vancouver BC Canada but I have found a block. I have a 1973 Opel gt and the Buick 215 is alittle too big for it so I want to build a v8 using the diamler block. I’m hoping to here is parts from another engine that is more common that I can use with this block. It would be helpful to be able to use a top end from 2 4 cylinder engines to bolt to the block so I can use the pistons from the engines so I would only need to find a crack for it. If I could find one of these engines I would rather buy it if I could afford it with shipping because I’m a beginner with mechanics. I’ve been looking around but haven’t found anything v8 that is smaller then the 3.5 Buick or Oldsmobile engine. I want something very light that’s aluminum so I won’t need to upgrade the suspension and other things in the opel gt. I think this engine is the best option or I will be forced to go with a v6 or v4. I could really use your advise on parts. If you think it would cost less to just buy a small v6 please let me know. Thank you

Even if there were heads that fit it would still be much cheaper and easier to fit a v6. Or stick with a four cylinder that makes more than, what, 90hp?

The Daimler V8 is a finicky beast and parts are hard to find. I would avoid it like the plague.

Were it me I’d use a modern engine the right size to suit the Opel’s mid engine design. Although you seem set on a V configuration, the original in line 4 could be well copied with something like a Miata engine, and you can make a lot of horses out of one of them.

The Rover( Buick 3.5) engine is a popular swap in this neck of the woods (NZ), no heavier, possibly lighter and more powerful. Presumably, the larger versions of the same engine fit equally well. In NZ, the Daimler Lanchester Owners Club can supply parts for the original engines, including remanufactured heads. Not sure of the logistics of getting them to you, but it might be worth enquiring.

I would also consider looking at some of the more modern I-4 options such as the GM 2.4 Echo tech engines, it would require some electrical and Fuels system upgrades, but they make 175hp stock, and are a bit of a slant 4 and they lean a bit to the passenger side (not anything like a Chrysler slant 6 but still noticeable)
The height might be an issue as the modern DOHC engines are quite a bit taller than the old school pushrod engines.
They a plentiful and inexpensive to purchase used. The RWD versions were only used in the Pontiac Solstice & Saturn Sky Models, but the FWD versions are much more plentiful.
And the 2.0 Turbo version was the engine used in the last Opel GT’s so a bit a brand lineage as well.

Just something to think about