actually, the 350 was probly a pontiac block, the 305 was chevy and the 403 was an olds engine as already stated. just about any pontiac block from 1965 thru end of production of 326cu in. all the way to 455 will look the same in 1/24 or 1/25 scale... the internals would change but external config of those blocks were the same until you get to the more esoteric configs like tri-power or dual quad.
I don't use IE so have no direct info on that, but... If you get a "notice" or message on your computer that you need to "update" something and you're not sure if the message is valid, go to the source of the software to check for updates. I.E. if you see a message to update Flash player, go to Adobe.com to get your update, if you see a message to update Explorer, go to Microsoft. If you click on any link in a questionable update message, you may be inviting malware or a virus to your computer and if you don't keep tools like Malwarebytes and/or Windows Defender active and up to date then you have just caused your own problem. Also be sure to read through all screens of any software that you install that's free, many include a free search utility that gets embedded in your browser and causes other problems. In most cases there is no need you any extra "search bar" utility...if you like them that's fine but you may end up having to pay to get them cleaned off your computer.
sounds like you may have been infected by a "root kit", malwarebytes has a root kit remover also... mbar.exe is the installer, you should be able to get it from the "More Tools" tab of the Malwarebytes application. if that doesn't take care of the problem I suggest Rogue Killer as the next course of action, it's what I had to use when malwarebytes was insufficient to remove a stubborn problem.
brief research indicates this may be caused by malware, the solution posted in the research was to run Malwarebytes anti-malware, there is a free version that is handy for cleaning and a premium version for proactive protection ( I had to install this version on my mothers computer).
they may not let you down grade the software either, you won't know till you try uninstalling and then trying to install the version you purchased. at that point you may be screwed. I can't really fault Adobe on this, they provide support and version updates... in order to keep generating revenue they have to go to annual fee structure. I choose not to support that type of structure by using other software that has most of the functionality at a sixth of the cost and it does what I need it to do. Antivirus software used to be a buy it and get support for life, a few years ago they went to annual fees per machine install, that is when I researched a less expensive option.
I know this will be a can of worms and I don't work for any software company...but... The software company sold you a license to "legally" use their software for a specified amount of time (when you "bought into the cloud"). In previous years a software license could be purchased without annual fees for support or updates, that is no longer true due to the cost of software updates but in the past we didn't have as many hackers as we seem to have now that can exploit any little software loophole. I'm not defending software companies, just trying to shine some light on a misconception. You do not own any software that you think you have just purchased, you have paid for the right to use it per the EULA (End User Licensing Agreement).
based on my own experience, it seems if you get photoshop versions newer than 4 or 5 that you get mired in the photoshop cloud tar pit... that is one of the reasons I haven't tried to set that up for my wife who uses InDesign for newsletter creation. Anyone that has a business need for photoshop and can get their company to pay for it is lucky, me...I will stick with paintshop pro at a tenth of the cost of photoshop.