301 it. You won't get 100%, but you'll get close.
But the most important issue that I want to bring up is your new site. Compared to your old site, it's not as functional. I'm all for updating technology, but you need to keep the functionality. I like that you've got the phone number nice and big at the top of both websites. However, I feel like I need to hunt and peck to find any real information on your new site. Your old site is content-rich, which is one reason why it ranks so well in Google.
If you can keep most pertinent information on the homepage and avoid the need to go to other pages, you'll get a better response. Your new navigation menu is super large and you've got a useless slider that takes up the majority of the space above the fold. Look up the stats on sliders. Users don't really use them or like them. They come to your website to look for information and skim for content, NOT to sit there and watch pretty pictures go by.
If I were you, I'd turn that old site of yours into a responsive Wordpress template. Update the look and feel a little bit, but otherwise leave it alone. It's really good functionality wise and all the information is right there above the fold, right at your user's fingertips. If you don't have the skills/time to turn the old site into a responsive Wordpress template, then find someone on Fiverr. They can usually do it for less than $100 and they'll probably throw in a redesign along with it so it looks a little more updated.
My business is in an area with VERY expensive AdWords cost per click, so maximizing conversions is my #1 priority. I'm just guessing, but I think your new site will get maybe a 1/5 conversion, which is pretty low. Your old one will probably get a 1/3 to 1/2, which is considerably better. You probably won't notice right away if new visitors to your website aren't converting because of past customers, but I guarantee you your new site doesn't convert very well compared to your old one. My conversion rate is close to 90% with my website design. If it weren't, I'd be out of business. I've tested many different website layouts and designs, and invariably the more information I keep on the main page and the more call to actions I have, the better the conversion. Your new website has absolutely no call to action and the information on the homepage is very minimal. Users generally don't click on links that don't look like links (like your "in our shop" links) and they don't want to have to click on a bunch of different pages to get the information they need.
The best thing about keeping your old content is it's 100% guaranteed to retain your ranking. There's no way your new site is going to rank as well as your old site because it has virtually no information on the homepage.
I don't mean to bring you bad news or bash your design or anything. But these Wordpress templates don't work very well at converting visitors into paying customers. Trust me, I've tried. I have to work my butt off every time I need to redo my website because you can't just buy a decent Wordpress template anymore because what I'm talking about is an "old" design. But what matters is whether or not your website generates calls and emails, not how modern it is. But I think you can have a mix of both.