Having never done a swap I can't say how hard it is, but building and installing a U20 will be miles ahead of a swap in terms of ease. Michael has the SR conversion down to a science and is always a helpful guy so that makes things easier in that you don't have to reinvent the wheel. But, you're likely to have to change a number of additional things like gauges, weld in engine mounts, etc.
Other things to consider as the world changes would be emissions... a U20 will be dirty vs an SR with a cat. I don't mean to be a downer, but with what I'm hearing about the goal of reducing carbon emissions 45% by 2030 (only 8.5 years away!) I don't know what legal impact this may have on cars like ours in general, let alone swapped vs stock (but very likely a U20 without emissions on it). It may be that a car that is "stock" or can be made to look stock will have a better chance of being allowed vs a cleaner swapped car that is obviously not stock (ya I know, doesn't make sense but neither does government sometimes). This is ALL speculation, but I think the time may be approaching where this could become an issue and you may want to factor that into your decision. I've converted my U20 to EFI and a better ignition/timing system, but while I'm sure it's "cleaner" there's no way I could get anywhere near clean as what an SR would do. I might be able to add a cat but that won't change the cam or 40 years of engine technology.
Regardless, we're here to help! (Oh YEAH Greg, that's A LOT of help

!)