I'm not sure how much you know about HFT already?
You mentioned ' Compete/Competitive ' in your post. What are you thinking of competing against?
In the UKAHFT National series this year in 2015 there were only 4 springer shooters that qualified with 6 out of 9 shoots. The lad who won it by a mile only shot the minimum number of shoots.
It's fine shooting springer in HFT but you are probably best realising that you are only competing against yourself and the courses ( that's the same for most shooters in HFT ).
So you don't need a super tuned rifle to do that. Anything decent that will give you under an inch groupings HFT prone at 45 yards will be fine. Most people will go for a TX200 or HW77/97. So if you like the 77s then they will be fine. A 77 out of the box will be fine but one that has had a degrease and basic tune with good fitting guides is even nicer to shoot.
0.177 is most sensible. 0.22 will just be even harder.
I shot springer in HFT for 12 years or more.
If it's what you want to do and you will enjoy it then do it. You probably need to realise that springer HFT is not for the faint hearted. Shooting a recoiling rifle is harder than a PCP. So a lot of people will say that they get more satisfaction out of shooting a springer. Yeah yeah that's fine but you have to realise that HFT courses have evolved and with people using top end pcps and a rock steady HFT prone stance the courses have become very tough. Lots of small kill zones and angled shots etc. This had to happen to stop pcp guys clearing courses.
The problem is that when you get a windy day now a lot of targets can become a lottery.
So on a stillish day a decent HFT course will be very hard work for a springer shooter. On a windy day ... good luck. Add to this that there is little gain from having supported positionals with a recoiling gun. Add to this that those angled shots are tricky for the pcp men with your body twisted at all angles ... try that with a springer where you have to change position of your hands on the stock to get to the different angles ( poi changes with different positions of hold on a springer ).
Look at the scores that springer men get at HFT courses. The very best ones will sometimes get into the 50's. Most springer shooters are well down in the 40's. So you are spending 3 hours in a wood and probably only hitting half of the targets. Most of the time you won't have a clue why you have missed.
There's only a few people shooting springer for a reason.
Scopes ... it's up to what suits you and your eyes. It also depends on whether you are good at ranging by eye or whether you will want the scope to help you there with blur or with bracketing.
The only useful piece of advice re scopes is to go to a club and look through plenty of scopes and see what suits you. Please don't buy until you've done this. I'd also buy second hand for a couple of years until you realise what you actually want.
General advice is something around 8 - 10x mag with a front objective lens of no more than 40mm ( pref smaller ). A ret with multi aim points ... mil dot, half mil dot, tree etc. Don't get the MTC Connects as you have to have your eye right up to the lens and the recoil will cause a problem.
Don't buy cheap on glass unless you find a cheapish scope that really suits you. Get decent glass. Get decent mounts. Make sure the scope and mounts are set up properly.
Go break your heart on courses.