Best engine for a 356 Speedster?

[70Manx]

I'm building a 356 Speedster and would like a recommendation on the best engine size and associated components (carb, cam, etc.) for the kit car. I plan to use the car mostly around town, but it will definately see some highway use (interstate travel to the beach, etc.). I'd like something peppy off the line at a stop light, but I do not intend to race. I also want something that is very dependable and has longevity. I'm willing to consider a Type IV, but so far all I have built are type I engines (I would like to build this engine for the 356 as well). I have a 3:88 trans for the car. Tires/wheels will be pretty much stock height. i'd also like to know what cooling would be best (Porsche fan shroud, oil cooler with temp, or stock shroud). Finally, When suggesting options let's keep price in mind - nothing outrageous please - just a good peppy economical engine set up.
Your suggestions and reasoning would be appreciated.
Jake, if you sell a kit, I'd like to know more about it.
Thanks,
Steve