The 65 or 80 will be the hardness of the bush. The scale is 0-100, 100 being hard, 0 being soft. Generally, from past experience, standard rubber bushes tend to be about 40 shore, with polyurethane replacements generally 60 for "uprated" or 80 for "hard".
If it's a track car I'd say go for 80. If you plan on road driving I would say 65. Harder isn't always better. Yes, it will provide less movement being harder but it will also transmit a broader range of frequencies from the engine to the shell and on to you. You may find holding it at certain revs will make the car vibrate where it didn't before and vice versa, this would all be tuned out in modern cars by NVH (Noise Vibration Harshness) where, long story short, they stick microphones on the body, measure frequencies and generally stick on lumps of metal to counteract the frequency and dampen it. I've never seen any on a Polo though so maybe just bung more sound deadening in if it's an issue.