It's a worldly debate many end up in once they familiarize themselves with all of the info.

Older, lighter, somewhat slower car VS newer, faster, heavier and with more comfort.

As far as performance goes, many folks have discovered that the 3.7 short block is a straight swap that would convert the 35HR into a 37HR which is quite worth the effort if you're planning on staying with the car.

You'll have to put these things down on paper and compare however the 35 ends up being the most cost effective chassis for your project. In reality you'll just be a bit slower than a 37 however over time, depending how much time you keep the car for a short block is not that much money, just a ton of work but totally worth it.

Where the 37 block swap comes in play is during tuning. The HR has 4 VTCs and can control timing from the cams individually, the block offers a high compression 3.7 components that have been proven to rev to 7.5k. Tune those heads and you'll be right past the 320whp mark that most 37 owners get to.