Good luck on swapping an sv engine into a four cylinder Scout 800! I've done one of these and while it's not impossible, I'd never attempt another one in my lifetime. And I've done/do some pretty tuff fabrication work!
Sounds simple huh? Not hardly!
The vertical flow radiator for use in a s800 v8 application is what you would need, it will bolt directly to the s80 core support, you "might" have to make four new mounting holes in the support. You will not find a new one unless someone has a nos unit stuck back. The one rig I worked on with the owner regarding the impossible engine swap,...we used a Scout II radiator that had the core support totally removed and moved forward and then cut out for the sii radiator.
From the doghouse forward, a sv-powered s800 is completely different in the inside sheetmetal, doghouse, core support and steering areas!
The oem Scout 800 v8 (either 266 or 304) used a strange combination mechanical clutch throwout/bellhousing system also, not at all similar to a Scout 80 with the t-90 three speed and the hydraulic clutch release. The four cylinder tranny apps use a "pancake" bellhousing and using a t90 behind any engine in my book is a waste, the ratios don't match any engine power characteristics, and behind the 152 the combo is down right dangerous. Yes...I do have one myself and I've delt with many of these!
Here's some pics of the pancake bell (four cylinder) tied into a t-18 four speed I'm doing for my rig:
http://www.forums.IHPartsAmerica.com/transmission-tech/911-Scout-80-t18-four-speed-swaperoo.html