DONT THINK SO...(read)
My friends,
I have never tried to fit a supra head and I wouldnt waste my time on it. Sure it is an excellent head with the 4 valves, centered spark plug, cross flow, dohc but there are LOTS of factors to consider for it to be possible.
Let me make a short list.
1. Cilinder center to cilinder center distance - it cannot be close to equal, it HAS to be exactly equal, something that i really really doubt.
2. Oil passages to the cam towers there are just one or two places that the oil passes from the block to the head in the L28 block, they would have to match the supra head.
3. Distribution chain geometry - sure you could get a chain any length but what about the guides, the tensioners and the gears?
4. The gears - you will use one of the two chains (supra or nissan) so all gears would have to match.
5. Water passages - they have to coordinate
6. Gasket - decisions decisions.....which gasket to use? supra or nissan?

7. Head bolts? fine, and you?
I think I can come up with about 3-4 more issues if those are not enough.
So if you want a cross flow, twin cam nissan engine get a RD26 from a skyline or contact OS Giken in Japan for the twin cam head for the L28 which I dont thing is available, and if so, it should cost more than $5k.
So dont bother. Want power? Go turbo.
CarlosZXT