As far as quality kits, Hinson's are a better quality, but Granny's are cheaper. Personally I would go with Granny's, because I am a poor ass college student and money is always the biggest factor in every single project I undertake.
As far as easy of install, carbuerated engines are the easiest, but EFI will give you better gas mileage and ease of tuning. RX-7's are really one of those project cars where everything just depends on what you have the money and skill for.