I'll offer you another option, since you seem to be interested in the car's value as a collector - have the car painted in the original color, and then have the car vinyl wrapped in the color of your choice. And, since it's just a wrap that you can peel off whenever, you can wrap it whatever color you like. As a bonus, the wrap will also serve to protect the paint underneath.
Since you're doing an engine-in respray, meaning the car is clearly not doing a complete color change (inside, outside, everywhere), this paint job isn't going to help the value of the car in that regard, and a collector who wants an original car will have to have the car repainted anyway.